Method of manufacturing semiconductor device and substrate processing apparatus

ABSTRACT

Provided is a method of manufacturing a semiconductor device. The method includes: (a) forming an oxide film having a predetermined thickness on a substrate by alternately repeating: (a-1) forming a layer containing a predetermined element on the substrate by supplying a source gas containing the predetermined element into a process vessel accommodating the substrate and exhausting the source gas from the process vessel; and (a-2) changing the layer containing the predetermined element into an oxide layer by supplying an oxygen-containing gas and an hydrogen-containing gas into the process vessel, wherein inside of the process vessel is under a heated atmosphere having a pressure lower than an atmospheric pressure; and exhausting the oxygen-containing gas and the hydrogen-containing gas from the process vessel; and (b) modifying the oxide film formed on the substrate by supplying the oxygen-containing gas and the hydrogen-containing gas into the process vessel, wherein the inside of the process vessel is under the heated atmosphere having the pressure lower than the atmospheric pressure, and exhausting the oxygen-containing gas and the hydrogen-containing gas from the process vessel.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuous application of U.S. patent applicationSer. No. 13/553,968 filed on Jul. 20, 2012, which is a continuation ofU.S. patent application Ser. No. 12/949,256 filed on Nov. 18, 2010,which issued as U.S. Pat. No. 8,252,701 on Aug. 28, 2012, which claimspriority, under 35 U.S.C. §119, to Japanese Patent Application No.2009-265432 filed on Nov. 20, 2009 and Japanese Patent Application No.2010-215398 filed on Sep. 27, 2010 in the Japanese Patent Office, theentire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing asemiconductor device, the method including a process of forming a thinfilm on a substrate, and a substrate processing apparatus suitable forthe process.

2. Description of the Related Art

In one of processes of manufacturing a semiconductor device, a siliconoxide film or a metal oxide film (hereinafter, such films will becollectively referred to as oxide films) is formed by a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.Generally, it is known that electric characteristics of a semiconductordevice are improved when films of the semiconductor device are formed athigh temperatures. The reason for this may be that the concentrations ofimpurities of the films are reduced and the quality of the film isimproved if the films are formed at high temperatures. For example,there is a method of forming a silicon oxide film (high temperatureoxide (HTO) film) at a high temperature of about 800° C. by a CVD methodusing an inorganic material such as SiH₂Cl₂ gas and N₂O gas (e.g., referto Patent Document 1).

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2001-85333

However, when a silicon oxide film or a metal oxide film is formed by aCVD or ALD method, a source gas such as a silicon source may undergoself-reaction at a higher temperature to generate a contaminant, or HClor Cl₂ generated from the source gas may act as an etchant todeteriorate film thickness uniformity. Therefore, it may be difficult toform a silicon oxide film or a metal oxide film at a higher temperatureby a CVD or ALD method.

There is a method of forming an oxide film by diffusion such as a dryoxidation method or a wet oxidation method. However, as size reductionproceeds, if an oxide film is formed by diffusion, a material (forexample, silicon) lying under the oxide film is consumed while the oxidefilm is formed. Therefore, it may be improper to use a diffusion methodto form an oxide film in a small region.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method ofmanufacturing a semiconductor device and a substrate processingapparatus that are designed to improve the quality of an oxide filmwhile avoiding risks of a high temperature oxide film forming process,and thus to improve electric characteristics of a semiconductor device.Another object of the present invention is to provide a method ofmanufacturing a semiconductor device and a substrate processingapparatus that are designed to minimize consumption of an under-layermaterial when an oxide film is formed, so as to make the oxide filmsuitable for constructing a fine structure.

According to an aspect of the present invention, there is provided amethod of manufacturing a semiconductor device, including:

(a) forming an oxide film having a predetermined thickness on asubstrate by alternately repeating: (a-1) forming a layer containing apredetermined element on the substrate by supplying a source gascontaining the predetermined element into a process vessel accommodatingthe substrate and exhausting the source gas from the process vessel; and(a-2) changing the layer containing the predetermined element into anoxide layer by supplying an oxygen-containing gas and anhydrogen-containing gas into the process vessel, wherein an inside ofthe process vessel is under a heated atmosphere having a pressure lowerthan an atmospheric pressure, and exhausting the oxygen-containing gasand the hydrogen-containing gas from the process vessel; and

(b) modifying the oxide film formed on the substrate by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under the heatedatmosphere having the pressure lower than the atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel.

According to another aspect of the present invention, there is provideda substrate processing apparatus including:

a process vessel configured to accommodate a substrate;

a heater configured to heat an inside of the process vessel;

a source gas supply system configured to supply a source gas containinga predetermined element into the process vessel;

an oxygen-containing gas supply system configured to supply anoxygen-containing gas into the process vessel;

a hydrogen-containing gas supply system configured to supply ahydrogen-containing gas into the process vessel;

an exhaust system configured to exhaust the inside of the processvessel;

a pressure regulator configured to control pressure of the inside of theprocess vessel; and

a controller configured to control the heater, the source gas supplysystem, the oxygen-containing gas supply system, the hydrogen-containinggas supply system, the exhaust system, and the pressure regulator so asto perform:

(a) forming an oxide film having a predetermined thickness on thesubstrate by alternately repeating: (a-1) forming a layer containing thepredetermined element on the substrate by supplying the source gas intoa process vessel accommodating the substrate and exhausting the sourcegas from the process vessel; and (a-2) changing the layer containing thepredetermined element into an oxide layer by supplying anoxygen-containing gas and an hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under a heatedatmosphere having a pressure lower than an atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel; and

(b) modifying the oxide film formed on the substrate by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel, wherein the process vessel is under the heated atmosphere havingthe pressure lower than the atmospheric pressure, and exhausting theoxygen-containing gas and the hydrogen-containing gas from the processvessel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a vertical process furnace of asubstrate processing apparatus that can be suitably used according to anembodiment of the present invention, FIG. 1 illustrating a verticalsectional view of the process furnace.

FIG. 2 is a sectional view taken along line A-A of FIG. 1 forschematically illustrating the vertical process furnace according to theembodiment of the present invention.

FIG. 3 is a flowchart for explaining process flows according to anembodiment of the present invention.

FIG. 4 is a view illustrating gas supply timings of a process sequencefor an exemplary case of forming a silicon oxide film on a substrateaccording to the embodiment of the present invention.

FIG. 5 is a view illustrating gas supply timing of a process sequencefor an exemplary case of forming a zirconium oxide film on a substrateas a metal oxide film according to an embodiment of the presentinvention.

FIG. 6 is a view illustrating wafer etching rates of silicon oxide filmsbefore and after modification treatments are performed to the siliconoxide films formed in a film-forming process of an embodiment of thepresent invention.

FIG. 7 is a view illustrating the concentration of an impurity (H) in asilicon oxide film formed in a process sequence according to anembodiment of the present invention.

FIG. 8 is a view illustrating the concentration of an impurity (Cl) in asilicon oxide film formed in a process sequence according to anembodiment of the present invention.

FIG. 9 is a view illustrating gas supply timing of a process sequencefor an exemplary case where a modification process is performed during afilm-forming process according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventors have studied a method of forming an oxide film such as asilicon oxide film or a metal oxide film at a relatively low temperatureto avoid risks of a high temperature film-forming process and thenperforming a predetermined modification treatment to the oxide film. Asa result, the inventors have found the following fact. After performinga process of forming an oxide film on a substrate, if a modificationprocess is performed to the oxide film formed on the substrate bysupplying an oxygen-containing gas and a hydrogen-containing gas to theoxide film of the substrate under a heated atmosphere kept at a pressurelower than an atmospheric pressure, impurities of the oxide film can belargely reduced, and the quality of the oxide film can be significantlyimproved. In addition, it has been found that when the oxide film isformed, consumption of an under-layer material can be minimized to makethe oxide film suitable for constructing a fine structure.

In the oxide film forming process, an oxide film such as a silicon oxidefilm or a metal oxide film may be formed by a chemical vapor deposition(CVD) method. Alternatively, an oxide film may be formed by an atomiclayer deposition (ALD) method. In an embodiment of the presentinvention, an oxide film having a predetermined thickness is formed on asubstrate by alternately repeating: a process of forming a layercontaining a predetermined element on the substrate by supplying asource gas containing the predetermined element into a process vesselwhere the substrate is accommodated and exhausting the source gas fromthe process vessel; and a process of changing the layer containing thepredetermined element into an oxide layer by supplying anoxygen-containing gas and a hydrogen-containing gas into the processvessel which is heated and kept at a pressure lower than atmosphericpressure and exhausting the oxygen-containing gas and thehydrogen-containing gas from the process vessel. For example, thepredetermined element may be a semiconductor element such as silicon(Si), or a metal element such as zirconium (Zr), hafnium (Hf), titanium(Ti), or aluminium (Al).

In the oxide film forming process, the process of forming the layercontaining the predetermined element is performed in a condition where aCVD reaction can be caused. At this time, a predetermined element layeris formed as the layer containing the predetermined element constitutedby less than one atomic layer to several atomic layers. The layercontaining the predetermined element may be an adsorption layer of thesource gas containing the predetermined element (hereinafter simplyreferred to as a source gas). The predetermined element layer is ageneral term used to denote a layer made of the predetermined element,such as a continuous layer, a discontinuous layer, and a thin film inwhich such layers are overlapped. In addition, a continuous layer madeof the predetermined element may also be called “a thin film.” Inaddition, the adsorption layer of the source gas is a term including acontinuous chemical adsorption layer formed by chemical adsorption ofmolecules of the source gas and a discontinuous chemical adsorptionlayer formed by chemical adsorption of molecules of the source gas.Furthermore, the expression “a layer less than one atomic layer” is usedto denote a discontinuous atomic layer. In a condition where the sourcegas decomposes by itself, the predetermined element layer is formed onthe substrate by deposition of the predetermined element on thesubstrate. In a condition where the source gas does not decompose byitself, a source gas adsorption layer is formed on the substrate byadsorption of the source gas on the substrate. The former case where thepredetermined element layer is formed on the substrate is morepreferable than the latter case where the source gas adsorption layer isformed on the substrate because the film-forming rate of the former caseis higher than that of the latter case.

In the oxide film film-forming process, the process of changing thelayer containing the predetermined element into the oxide layer isperformed by generating an oxidizing species containing oxygen byreaction between the oxygen-containing gas and the hydrogen-containinggas in the process vessel which is heated and kept at a pressure lowerthan atmospheric pressure and oxidizing (changing) the layer containingthe predetermined element into the oxide layer by using the oxidizingspecies. By this oxidizing treatment, oxidizing power can be largelyincreased as compared with the case where only an oxygen-containing gasis supplied. That is, by adding a hydrogen-containing gas to anoxygen-containing gas under a depressurized atmosphere, oxidizing powercan be largely increased as compared with the case where only anoxygen-containing gas is supplied. The process of changing the layercontaining the predetermined element into the oxide layer can beperformed under a depressurized atmosphere without using plasma.Alternatively, in the process of changing the layer containing thepredetermined element into the oxide layer, one or both of theoxygen-containing gas and the hydrogen-containing gas may be activatedby plasma.

The oxide film having a predetermined thickness is formed on thesubstrate by alternately repeating: the process of forming the layercontaining the predetermined element, and the process of changing thelayer containing the predetermined element into the oxide layer. Next,the oxide film having a predetermined thickness is modified. In aprocess of modifying the oxide film having a predetermined thickness, anoxygen-containing gas and a hydrogen-containing gas are allowed to reactwith each other in the process vessel which is heated and kept at apressure lower than atmospheric pressure to generate an oxidizingspecies containing oxygen, and the oxide film is modified by using theoxidizing species. By this modification treatment, impurities includedin the oxide film can be largely reduced as compared with the case whereonly an oxygen-containing gas is supplied. That is, it was found thatthe effect of removing impurities from a film was largely improved byadding a hydrogen-containing gas to an oxygen-containing gas under adepressurized atmosphere as compared with the case where only anoxygen-containing gas was supplied. In addition, by this modificationtreatment, impurities included in the oxide film can be largely reducedas compared with the case where only N₂ gas is supplied, that is, thecase where N₂ annealing is performed. Therefore, electriccharacteristics of the oxide film can be improved. The process ofmodifying the oxide film can be performed under a depressurizedatmosphere without using plasma. Alternatively, in the process ofmodifying the oxide film, one or both of the oxygen-containing gas andthe hydrogen-containing gas may be activated by plasma.

The present invention is provided based on the knowledge of theinventors. Hereinafter, an embodiment of the present invention will nowbe described with reference to the attached drawings.

FIG. 1 is a schematic view illustrating a vertical process furnace 202of a substrate processing apparatus that can be suitably used accordingto an embodiment of the present invention, FIG. 1 illustrating avertical sectional view of the process furnace 202. FIG. 2 is asectional view taken along line A-A of FIG. 1 for schematicallyillustrating the vertical process furnace 202 according to theembodiment of the present invention. However, the present invention isnot limited to the substrate processing apparatus of the currentembodiment. For example, the present invention can be applied to othersubstrate processing apparatuses such as a substrate processingapparatus having a single-wafer type, hot wall type, or cold wall typeprocess furnace.

As shown in FIG. 1, the process furnace 202 includes a heater 207 as aheating unit (heating mechanism). The heater 207 has a cylindrical shapeand is vertically installed in a state where the heater 207 is supportedon a heater base (not shown) which is a holding plate. As describedlater, the heater 207 is also used as an activation mechanism foractivating gas by heat.

Inside the heater 207, a reaction tube 203 constituting a reactionvessel (process vessel) is installed concentrically with the heater 207.The reaction tube 203 is made of a heat-resistant material such as aquartz (SiO₂) or silicon carbide (SiC) and has a cylindrical shape witha closed top side and an opened bottom side. The hollow part of thereaction tube 203 forms a process chamber 201 and is configured toaccommodate substrates such as wafers 200 by using a boat 217 (describedlater) in a manner such that the wafers 200 are horizontally positionedand vertically arranged in multiple stages.

At the lower part of the reaction tube 203 in the process chamber 201, afirst nozzle 233 a as a first gas introducing part, and a second nozzle233 b as a second gas introducing part are installed through thereaction tube 203. A first gas supply pipe 232 a and a second gas supplypipe 232 b are connected to the first nozzle 233 a and the second nozzle233 b, respectively. In addition, a third gas supply pipe 232 c isconnected to the second gas supply pipe 232 b. In this way, at thereaction tube 203, two nozzles 233 a and 233 b, and three gas supplypipes 232 a, 232 b, and 232 c, are installed, and it is configured suchthat a plurality of kinds of gases, here, three kinds of gases, can besupplied into the process chamber 201.

At the first gas supply pipe 232 a, a flow rate controller (flow ratecontrol unit) such as a mass flow controller (MFC) 241 a, and an on-offvalve such as a valve 243 a are sequentially installed from the upstreamside of the first gas supply pipe 232 a. In addition, a first inert gassupply pipe 232 d is connected to the downstream side of the valve 243 aof the first gas supply pipe 232 a. At the first inert gas supply pipe232 d, a flow rate controller (flow rate control unit) such as a massflow controller 241 d, and an on-off valve such as a valve 243 d aresequentially installed from the upstream side of the first inert gassupply pipe 232 d. In addition, the first nozzle 233 a is connected tothe tip of the first gas supply pipe 232 a. In an arc-shaped spacebetween the inner wall of the reaction tube 203 and the wafers 200, thefirst nozzle 233 a is erected in a manner such that the first nozzle 233a extends upward from the lower side to the upper side along the innerwall of the reaction tube 203 in a direction in which the wafers 200 arestacked. That is, the first nozzle 233 a is installed at a side of awafer arrangement region where wafers 200 are arranged. The first nozzle233 a is an L-shaped long nozzle. Gas supply holes 248 a are formedthrough the lateral surface of the first nozzle 233 a. The gas supplyholes 248 a are formed toward the centerline of the reaction tube 203 sothat gas can be supplied toward the wafers 200 through the gas supplyholes 248 a. The gas supply holes 248 a are formed at a plurality ofpositions along the lower side to the upper side of the reaction tube203, and the gas supply holes 248 a have the same size and are arrangedat the same pitch.

A first gas supply system is constituted mainly by the first gas supplypipe 232 a, the mass flow controller 241 a, and the valve 243 a. Thefirst nozzle 233 a may be included in the first gas supply system. Inaddition, a first inert gas supply system is constituted mainly by thefirst inert gas supply pipe 232 d, the mass flow controller 241 d, andthe valve 243 d. The first inert gas supply system functions as a purgegas supply system.

At the second gas supply pipe 232 b, a flow rate controller (flow ratecontrol unit) such as a mass flow controller (MFC) 241 b, and an on-offvalve such as a valve 243 b are sequentially installed from the upstreamside of the second gas supply pipe 232 b. In addition, a second inertgas supply pipe 232 e is connected to the downstream side of the valve243 b of the second gas supply pipe 232 b. At the second inert gassupply pipe 232 e, a flow rate controller (flow rate control unit) suchas a mass flow controller 241 e, and an on-off valve such as a valve 243e are sequentially installed from the upstream side of the second inertgas supply pipe 232 e. In addition, the second nozzle 233 b is connectedto the tip of the second gas supply pipe 232 b. The second nozzle 233 bis installed in a buffer chamber 237 forming a gas diffusion space.

The buffer chamber 237 is installed in an arc-shaped space between thereaction tube 203 and the wafers 200 in a manner such that the bufferchamber 237 is located from the lower side to the upper side of theinner wall of the reaction tube 203 in a direction in which the wafers200 are stacked. That is, the buffer chamber 237 is installed at a sideof the wafer arrangement region. At an end of a wall of the bufferchamber 237 adjacent to the wafers 200, gas supply holes 248 c areformed to supply gas therethrough. The gas supply holes 248 c are formedtoward the centerline of the reaction tube 203 so that gas can besupplied toward the wafers 200 through the gas supply holes 248 c. Thegas supply holes 248 c are formed at a plurality of positions along thelower side to the upper side of the reaction tube 203, and the gassupply holes 248 c have the same size and are arranged at the samepitch.

The second nozzle 233 b is installed in the buffer chamber 237 at an endopposite to the end where the gas supply holes 248 c are formed, in amanner such that the second nozzle 233 b is erected upward along thelower side to the upper side of the inner wall of the reaction tube 203in a direction in which the wafers 200 are stacked. That is, the secondnozzle 233 b is installed at a side of the wafer arrangement region. Thesecond nozzle 233 b is an L-shaped long nozzle. Gas supply holes 248 bare formed through the lateral surface of the second nozzle 233 b. Thegas supply holes 248 b are opened toward the centerline of the bufferchamber 237. Like the gas supply holes 248 c of the buffer chamber 237,the gas supply holes 248 b are formed at a plurality of positions alongthe lower side to the upper side of the reaction tube 203. If there is asmall pressure difference between the inside of the buffer chamber 237and the inside of the process chamber 201, it may be configured suchthat the gas supply holes 248 b have the same size and are arranged atthe same pitch from the upstream side (lower side) to the downstreamside (upper side); however if the pressure difference is large, it maybe configured such that the size of the gas supply holes 248 b increasesor the pitch of the gas supply holes 248 b decreases as it goes from theupstream side to the downstream side.

In the current embodiment, since the size or pitch of the gas supplyholes 248 b of the second nozzle 233 b is adjusted from the upstreamside to the downstream side as described above, although the velocitiesof gas streams injected through the gas supply holes 248 b aredifferent, the flow rates of the gas streams injected through the gassupply holes 248 b can be approximately equal. Gas streams injectedthrough the respective gas supply holes 248 b are first introduced intothe buffer chamber 237 so as to reduce the velocity difference of thegas streams. That is, gas injected into the buffer chamber 237 throughthe gas supply holes 248 b of the second nozzle 233 b is reduced inparticle velocity and is then injected from the buffer chamber 237 tothe inside of the process chamber 201 through the gas supply holes 248 cof the buffer chamber 237. Owing to this structure, when gas injectedinto the buffer chamber 237 through the gas supply holes 248 b of thesecond nozzle 233 b is injected into the process chamber 201 through thegas supply holes 248 c of the buffer chamber 237, the flow rate andvelocity of the gas can be uniform.

A second gas supply system is constituted mainly by the second gassupply pipe 232 b, the mass flow controller 241 b, and the valve 243 b.The second nozzle 233 b and the buffer chamber 237 may be included inthe second gas supply system. In addition, a second inert gas supplysystem is constituted mainly by the second inert gas supply pipe 232 e,the mass flow controller 241 e, and the valve 243 e. The second inertgas supply system functions as a purge gas supply system.

At the third gas supply pipe 232 c, a flow rate controller (flow ratecontrol unit) such as a mass flow controller (MFC) 241 c, and an on-offvalve such as a valve 243 c are sequentially installed from the upstreamside of the third gas supply pipe 232 c. In addition, a third inert gassupply pipe 232 f is connected to the downstream side of the valve 243 cof the third gas supply pipe 232 c. At the third inert gas supply pipe232 f, a flow rate controller (flow rate control unit) such as a massflow controller 241 f, and an on-off valve such as a valve 243 f aresequentially installed from the upstream side of the third inert gassupply pipe 232 f. In addition, the tip of the third gas supply pipe 232c is connected to the downstream side of the valve 243 b of the secondgas supply pipe 232 b.

A third gas supply system is constituted mainly by the third gas supplypipe 232 c, the mass flow controller 241 c, and the valve 243 c. A partof the second nozzle 233 b and the buffer chamber 237 that are locatedat the downstream side of a junction part between the second gas supplypipe 232 b and the third gas supply pipe 232 c may be included in thethird gas supply system. In addition, a third inert gas supply system isconstituted mainly by the third inert gas supply pipe 232 f, the massflow controller 241 f, and the valve 243 f. The third inert gas supplysystem functions as a purge gas supply system.

A source gas containing a predetermined element, that is, a source gascontaining silicon (Si) as the predetermined element (silicon-containinggas) such as hexachlorodisilane (Si₂Cl₆, abbreviation: HCD) is suppliedfrom the first gas supply pipe 232 a into the process chamber 201through the mass flow controller 241 a, the valve 243 a, and the firstnozzle 233 a. That is, the first gas supply system is configured as asource gas supply system (silicon-containing gas supply system). At thistime, inert gas may be supplied from the first inert gas supply pipe 232d into the first gas supply pipe 232 a through the mass flow controller241 d and the valve 243 d.

Gas containing oxygen (oxygen-containing gas) such as oxygen (O₂) gas issupplied from the second gas supply pipe 232 b into the process chamber201 through the mass flow controller 241 b, the valve 243 b, the secondnozzle 233 b, and the buffer chamber 237. That is, the second gas supplysystem is configured as an oxygen-containing gas supply system. At thistime, inert gas may be supplied from the second inert gas supply pipe232 e into the second gas supply pipe 232 b through the mass flowcontroller 241 e and the valve 243 e.

Gas containing hydrogen (hydrogen-containing gas) such as hydrogen (H₂)gas is supplied from the third gas supply pipe 232 c into the processchamber 201 through the mass flow controller 241 c, the valve 243 c, thesecond gas supply pipe 232 b, the second nozzle 233 b, and the bufferchamber 237. That is, the third gas supply system is configured as ahydrogen-containing gas supply system. At this time, inert gas may besupplied from the third inert gas supply pipe 232 f into the third gassupply pipe 232 c through the mass flow controller 241 f and the valve243 f.

In the current embodiment, O₂ gas and H₂ gas are supplied into theprocess chamber 201 (buffer chamber 237) through the same nozzle.However, for example, O₂ gas and H₂ gas may be supplied into the processchamber 201 through the different nozzles. However, if a plurality ofkinds of gases are supplied through the same nozzle, many merits can beobtained. For example, fewer nozzles may be used to reduce apparatuscosts, and maintenance works may be easily carried out. For example, ifO₂ gas and H₂ gas are supplied into the process chamber 201 throughdifferent nozzles, HCD gas may be supplied into the process chamber 201through the same nozzle as that used to supply the H₂ gas. In afilm-forming temperature range (described later), HCD gas and O₂ gas mayreact with each other although HCD gas and H₂ gas do not react with eachother. Therefore, it may be preferable that HCD gas and O₂ gas aresupplied into the process chamber 201 through different nozzles.

Inside the buffer chamber 237, as shown in FIG. 2, a first rod-shapedelectrode 269 which is a first electrode having a long slender shape,and a second rod-shaped electrode 270 which is a second electrode havinga long slender shape are installed in a manner such that the first andsecond rod-shaped electrodes 269 and 270 extend from the lower side tothe upper side of the reaction tube 203 in a direction in which wafers200 are stacked. Each of the first and second rod-shaped electrodes 269and 270 is parallel with the second nozzle 233 b. The first and secondrod-shaped electrodes 269 and 270 are respectively protected byelectrode protection pipes 275 which cover the first and secondrod-shaped electrodes 269 and 270 from the upper parts to the lowerparts thereof. One of the first and second rod-shaped electrodes 269 and270 is connected to a high-frequency power source 273 through a matchingdevice 272, and the other is grounded to the earth (referencepotential). Therefore, plasma can be generated in a plasma generationregion 224 between the first and second rod-shaped electrodes 269 and270. A plasma source, which is a plasma generator (plasma generatingunit), is constituted mainly by the first rod-shaped electrode 269, thesecond rod-shaped electrode 270, the electrode protection pipes 275, thematching device 272, and the high-frequency power source 273. The plasmasource is used as an activation mechanism for activating gas by usingplasma.

The electrode protection pipes 275 are configured such that the firstand second rod-shaped electrodes 269 and 270 can be inserted into thebuffer chamber 237 in a state where the first and second rod-shapedelectrodes 269 and 270 are respectively isolated from the atmosphere ofthe buffer chamber 237. If the insides of the electrode protection pipes275 have the same atmosphere as the outside air (atmosphere), the firstand second rod-shaped electrodes 269 and 270 that are respectivelyinserted in the electrode protection pipes 275 may be oxidized due toheat emitted from the heater 207. Therefore, an inert gas purgemechanism is installed to prevent oxidation of the first rod-shapedelectrode 269 or the second rod-shaped electrode 270 by filling orpurging the insides of the electrode protection pipes 275 with inert gassuch as nitrogen to maintain the oxygen concentration of the insides ofthe electrode protection pipes 275 at a sufficiently low level.

At the reaction tube 203, an exhaust pipe 231 is installed to exhaustthe inside atmosphere of the process chamber 201. A vacuum pump 246which is a vacuum exhaust device is connected to the exhaust pipe 231through a pressure sensor 245 which is a pressure detector (pressuredetecting part) configured to detect the inside pressure of the processchamber 201 an auto pressure controller (APC) valve 244 which is apressure regulator (pressure regulating unit). The APC valve 244 is anon-off valve, which can be opened and closed to start and stop vacuumevacuation of the inside of the process chamber 201 and can be adjustedin degree of valve opening for pressure adjustment. By controlling thedegree of opening of the APC valve 244 based on pressure informationdetected by the pressure sensor 245 while operating the vacuum pump 246,the inside of the process chamber 201 can be vacuum-evacuated to apredetermined pressure (vacuum degree). Mainly, the exhaust pipe 231,the APC valve 244, the vacuum pump 246, and the pressure sensor 245constitute an exhaust system.

At the lower side of the reaction tube 203, a seal cap 219 is installedas a furnace port cover capable of hermetically closing the openedbottom side of the reaction tube 203. The seal cap 219 is configured tomake contact with the bottom side of the reaction tube 203 in aperpendicular direction from the lower side. For example, the seal cap219 is made of a metal such as stainless steel and has a disk shape. Onthe surface of the seal cap 219, an O-ring 220 is installed as a sealmember configured to make contact with the bottom side of the reactiontube 203. At a side of the seal cap 219 opposite to the process chamber201, a rotary mechanism 267 is installed to rotate a substrate holdingtool such as the boat 217 (described later). A shaft 255 of the boatrotary mechanism 267 penetrates the seal cap 219 and is connected to theboat 217. By rotating the boat 217 with the rotary mechanism 267, wafers200 can be rotated. The seal cap 219 is configured to be verticallymoved by an elevating mechanism such as a boat elevator 115 verticallyinstalled at the outside of the reaction tube 203. The boat elevator 115is configured so that the boat 217 can be loaded into and unloaded fromthe process chamber 201 by raising and lowering the seal cap 219 withthe boat elevator 115.

The boat 217, which is a substrate support tool, is made of aheat-resistant material such as quartz or silicon carbide and isconfigured to support a plurality of wafers 200 in a state where thewafers 200 are horizontally oriented and arranged in multiple stageswith the centers of the wafers 200 being aligned with each other. At thelower part of the boat 217, an insulating member 218 made of aheat-resistant material such as quartz or silicon carbide is installedso as to prevent heat transfer from the heater 207 to the seal cap 219.The insulating member 218 may include a plurality of insulating platesmade of a heat-resistant material such as quartz or silicon carbide, andan insulating plate holder configured to support the insulating platesin a state where the insulating plates are horizontally oriented andarranged in multiple stages.

Inside the reaction tube 203, a temperature sensor 263 is installed as atemperature detector, and by controlling power supplied to the heater207 based on temperature information detected by the temperature sensor263, desired temperature distribution can be attained at the inside ofthe process chamber 201. Like the first and second nozzles 233 a and 233b, the temperature sensor 263 has an L-shape and is disposed along theinner wall of the reaction tube 203.

A controller 121, which is a control unit (control device), is connectedto devices such as the mass flow controllers 241 a, 241 b, 241 c, 241 d,241 e, and 241 f; valves 243 a, 243 b, 243 c, 243 d, 243 e, and 243 f;the pressure sensor 245; the APC valve 244; the vacuum pump 246; theheater 207; the temperature sensor 263; the boat rotary mechanism 267;the boat elevator 115; the high-frequency power source 273; and thematching device 272. The controller 121 controls, for example, flowrates of various gases by using the mass flow controllers 241 a, 241 b,241 c, 241 d, 241 e, and 241 f; opening/closing operations of the valves243 a, 243 b, 243 c, 243 d, 243 e, and 243 f; opening/closing operationsof the APC valve 244 and pressure adjusting operations of the APC valve244 based on the pressure sensor 245; the temperature of the heater 207based on the temperature sensor 263; starting/stopping operations of thevacuum pump 246; the rotation speed of the boat rotary mechanism 267;ascending and descending operations of the boat 217 activated by theboat elevator 115; power supply to the high-frequency power source 273;and impedance adjusting operations using the matching device 272.

Next, an explanation will be given on an exemplary method of forming aninsulating film such as an oxide film on a substrate and modifyingchanging the oxide film by using the process furnace 202 of thesubstrate processing apparatus in one process of processes ofmanufacturing a semiconductor device. In the following description, thecontroller 121 controls parts of the substrate processing apparatus.

FIG. 3 illustrates process flows according to an embodiment of thepresent invention, and FIG. 4 illustrates gas supply timings accordingto a process sequence of the embodiment of the present invention.According to the process sequence of the current embodiment, an oxidefilm is formed on a substrate by alternately repeating: a process ofsupplying a source gas into the process vessel in which substrates areaccommodated and exhausting the source gas from the process vessel; anda process of supplying an oxygen-containing gas and ahydrogen-containing gas into the process vessel which is heated and keptat a pressure lower than atmospheric pressure and exhausting theoxygen-containing gas and the hydrogen-containing gas. Thereafter, theoxide film formed on the substrate is modified by supplying anoxygen-containing gas and a hydrogen-containing gas into the processvessel which is heated and kept at a pressure lower than atmosphericpressure and exhausting the oxygen-containing gas and thehydrogen-containing gas.

Hereinafter, a detailed explanation will be given. In the followingdescription of the current embodiment, an explanation will be given onan example where silicon oxide films (SiO₂ films) are formed onsubstrates as oxide films according to the process flows shown in FIG. 3and the process sequence shown in FIG. 4 by using HCD gas as a sourcegas, O₂ gas as an oxygen-containing gas, H₂ gas as a hydrogen-containinggas, and N₂ gas as a purge gas.

After a plurality of wafers 200 are charged into the boat 217 (wafercharging), as shown in FIG. 1, the boat 217 in which the plurality ofwafers 200 are supported is lifted and loaded into the process chamber201 by the boat elevator 115 (boat loading). In this state, the bottomside of the reaction tube 203 is sealed by the seal cap 219 with theO-ring 220 being disposed therebetween.

The inside of the process chamber 201 is vacuum-evacuated to a desiredpressure (vacuum degree) by using the vacuum pump 246. At this time, thepressure inside the process chamber 201 is measured by the pressuresensor 245, and based on the measured pressure, the APC valve 244 isfeedback-controlled (pressure adjustment). In addition, the inside ofthe process chamber 201 is heated to a desired temperature by using theheater 207. At this time, to obtain desired temperature distributioninside the process chamber 201, power to the heater 207 isfeedback-controlled based on temperature information measured by thetemperature sensor 263 (temperature adjustment). Next, the boat 217 isrotated by the rotary mechanism 267 to rotate the wafers 200.Thereafter, silicon oxide films are formed through a film-formingprocess by sequentially performing the following four steps.

<Film-Forming Process>

[Step 1]

The valve 243 a of the first gas supply pipe 232 a is opened to allow aflow of HCD gas through the first gas supply pipe 232 a. The flow rateof the HCD gas flowing through the first gas supply pipe 232 a iscontrolled by the mass flow controller 241 a. The HCD gas adjusted inflow rate is supplied through the gas supply holes 248 a of the firstnozzle 233 a into the process chamber 201 which is heated anddepressurized, and the HCD gas is exhausted through the exhaust pipe 231(HCD gas supply). At this time, the valve 243 d of the first inert gassupply pipe 232 d may be opened to supply inert gas such as N₂ gasthrough the first inert gas supply pipe 232 d. The flow rate of the N₂gas is adjusted by the mass flow controller 241 d and is supplied intothe first gas supply pipe 232 a. At this time, a mixture of the HCD gasand the N₂ gas is supplied through the first nozzle 233 a.

At this time, the APC valve 244 is properly controlled to keep theinside of the process chamber 201 at a pressure lower than atmosphericpressure, for example, in the range from 10 Pa to 1,000 Pa. The supplyflow rate of the HCD gas controlled by the mass flow controller 241 ais, for example, in the range from 20 sccm to 1,000 sccm (0.02 slm to 1slm). The supply flow rate of the N₂ gas controlled by the mass flowcontroller 241 d is, for example, in the range from 200 sccm to 1,000sccm (0.2 slm to 1 slm). The wafers 200 are exposed to the HCD gas, forexample, for 1 second to 120 seconds. The temperature of the heater 207is set such that a CVD reaction can be caused in the process chamber 201in the above-mentioned pressure range. That is, the temperature of theheater 207 is set such that the temperature of the wafers 200 can bekept in the range from 350° C. to 850° C., preferably, in the range from400° C. to 700° C. If the temperature of the wafers 200 is lower than350° C., decomposition and adsorption of HCD on the wafers 200 aredifficult. In addition, if the temperature of the wafers 200 is lowerthan 400° C., the film-forming rate becomes lower than a practicallyacceptable level. On the other hand, if the temperature of the wafers200 is higher than 700° C., particularly, higher than 850° C., CVDreaction becomes very active to reduce uniformity. Therefore, the wafers200 may be kept in the temperature range from 350° C. to 850° C.,preferably, in the range from 400° C. to 700° C.

By supplying HCD gas into the process chamber 201 under theabove-described conditions, silicon layers can be formed on the wafers200 (on the under-layer films of the wafers 200) as silicon-containinglayers each constituted by less than one atomic layer to several atomiclayers. The silicon-containing layers may be HCD adsorption layers. Thesilicon layer is a general term used to denote a layer made of silicon,such as a continuous silicon layer, a discontinuous silicon layer, and athin film in which such layers are overlapped. In addition, a continuouslayer made of silicon may also be called “a thin silicon film.” Inaddition, a HCD adsorption layer is a term including a continuouschemical adsorption layer formed by chemical adsorption of molecules ofHCD gas and a discontinuous chemical adsorption layer formed by chemicaladsorption of molecules of HCD gas. Furthermore, the expression “a layerless than one atomic layer” is used to denote a discontinuous atomiclayer. In a condition where HCD gas decomposes by itself, a siliconlayer is formed on a substrate by deposition of silicon on thesubstrate. In a condition where HCD gas does not decompose by itself, anadsorption layer of the HCD gas is formed on a substrate by adsorptionof the HCD gas on the substrate. If the thickness of asilicon-containing layer formed on the wafer 200 is greater than thethickness of several atomic layers, the silicon-containing layer may notbe entirely oxidized in step 3 (described later). In addition, theminimum of a silicon-containing layer that can be formed on the wafer200 is less than one atomic layer. Therefore, it may be preferable thatthe thickness of the silicon-containing layer is set to be in the rangefrom about the thickness of less than one atomic layer to about thethickness of several atomic layers. The case where a silicon layer isformed on a substrate is more preferable than the case where a HCD gasadsorption layer is formed on a substrate because the film-forming rateof the former case is higher than that of the latter case.

Instead of using HCD as a silicon-containing source, another source mayalternatively be used. Examples of such alternative sources include: aninorganic source such as TCS (tetrachlorosilane, SiCl₄), DCS(dichlorosilane, SiH₂Cl₂), and SiH₄ (monosilane); and an organic sourcesuch as aminosilane-based 4DMAS (tetrakisdimethylaminosilane,Si[N(CH₃)₂]₄), 3DMAS (trisdimethylaminosilane, (Si[N(CH₃)₂]₃H), 2DEAS(bisdiethylaminosilane (Si[N(C₂H₅)₂]₂H₂), and BTBAS(bistertiarybutylaminosilane (SiH₂[NH(C₄H₉)]₂).

Instead of using N₂ gas as inert gas, a rare gas such as Ar gas, He gas,Ne gas, and Xe gas may be used as the inert gas. If a rare gas such asAr or He gas that does not contain nitrogen (N) is used as the inertgas, a silicon oxide film having a low nitrogen (N) concentration(impurity concentration) can be formed. Therefore, it may be preferablethat a rare gas such as Ar gas and He gas is used as the inert gas. Thisis the same in steps 2 and 3 (described later).

[Step 2]

After the silicon-containing layers are formed on the wafers 200, thevalve 243 a of the first gas supply pipe 232 a is closed to interruptthe supply of HCD gas. At this time, the APC valve 244 of the exhaustpipe 231 is kept open, and the inside of the process chamber 201 isvacuum-evacuated by using the vacuum pump 246 so as to remove HCD gasremaining in the process chamber 201. At this time, if the valve 243 dis opened to supply inert gas such as N₂ gas into the process chamber201, the N₂ gas functions as a purge gas so that HCD gas remaining inthe process chamber 201 without participating in an reaction or afterparticipating in the formation of the silicon-containing layers can beremoved more efficiently (remaining gas removal).

At this time, the temperature of the heater 207 is set such that thetemperature of the wafers 200 can be in the range from 350° C. to 850°C., preferably, in the range from 400° C. to 700° C. like in the timewhen HCD gas is supplied. The supply flow rate of N₂ gas functioning asa purge gas is set to be in the range from 200 sccm to 1,000 sccm (0.2slm to 1 slm). Instead of using N₂ gas as a purge gas, a rare gas suchas Ar gas, He gas, Ne gas, and Xe gas may be used.

[Step 3]

After removing gas remaining in the process chamber 201, the valve 243 bof the second gas supply pipe 232 b is opened to allow a flow of O₂ gasthrough the second gas supply pipe 232 b. The flow rate of the O₂ gasflowing through the second gas supply pipe 232 b is controlled by themass flow controller 241 b. The O₂ gas adjusted in flow rate is suppliedthrough the gas supply holes 248 b of the second nozzle 233 b into thebuffer chamber 237 which is heated and depressurized. At the time, thevalve 243 c of the third gas supply pipe 232 c is also opened so that H₂gas can flow through the third gas supply pipe 232 c. The flow rate ofthe H₂ gas flowing through the third gas supply pipe 232 c is controlledby the mass flow controller 241 c. The H₂ gas adjusted in flow rate issupplied to the second gas supply pipe 232 b where the H₂ gas issupplied through the gas supply holes 248 b of the second nozzle 233 binto the buffer chamber 237 which is heated and depressurized. When theH₂ flows through the second gas supply pipe 232 b, the H₂ gas is mixedwith the O₂ gas in the second gas supply pipe 232 b. That is, a mixturegas of the O₂ gas and the H₂ gas is supplied through the second nozzle233 b. The mixture gas of the O₂ gas and the H₂ gas supplied into thebuffer chamber 237 is supplied through the gas supply holes 248 c of thebuffer chamber 237 into the process chamber 201 which is heated anddepressurized, and the mixture gas is exhausted through the exhaust pipe231 (O₂ gas+H₂ gas supply).

At this time, the valve 243 e of the second inert gas supply pipe 232 emay be opened to supply inert gas such as N₂ gas through the secondinert gas supply pipe 232 e. The flow rate of the N₂ gas is adjusted bythe mass flow controller 241 e and is supplied into the second gassupply pipe 232 b. In addition, the valve 243 f of the third inert gassupply pipe 232 f may be opened to supply inert gas such as N₂ gasthrough the third inert gas supply pipe 232 f. The flow rate of the N₂gas is adjusted by the mass flow controller 241 f and is supplied intothe third gas supply pipe 232 c. At this time, a mixture gas of the O₂gas, and H₂ gas, and N₂ gas is supplied through the second nozzle 233 b.Instead of using N₂ gas as inert gas, a rare gas such as Ar gas, He gas,Ne gas, and Xe gas may be used as inert gas.

At this time, the APC valve 244 is properly controlled to keep theinside of the process chamber 201 at a pressure lower than atmosphericpressure, for example, at a pressure ranging from 1 Pa to 1,330 Pa. Theflow rate of the O₂ gas controlled by the mass flow controller 241 b is,for example, in the range from 100 sccm to 10,000 sccm (0.1 slm to 10slm). The flow rate of the H₂ gas controlled by the mass flow controller241 c is, for example, in the range from 100 sccm to 10,000 sccm (0.1slm to 10 slm). In addition, the supply flow rates of the N₂ gascontrolled by the mass flow controllers 241 e and 241 f are, forexample, in the range from 0 sccm to 2,000 sccm (0 slm to 2 slm),respectively. In addition, the concentration of the H₂ gas (H₂/(H₂+O₂))is, for example, in the range from 25% to 50%, preferable, in the rangefrom 10% to 33%. That is, for example, it is set such that theproportion of O₂ gas is equal to or greater than the proportion of H₂gas. Preferably, the proportion of O₂ gas is set to be greater than theproportion of H₂ gas. That is, an oxygen-rich condition is made. Thewafers 200 are exposed to the O₂ gas and H₂ gas, for example, for 1second to 120 seconds. The temperature of the heater 207 is set suchthat the temperature of the wafers 200 can be kept, for example, in therange from 350° C. to 1,200° C. It was ascertained that oxidizing powercould be improved by adding H₂ gas to O₂ gas under a depressurizedatmosphere in the above-described temperature range. In addition, it wasalso ascertained that oxidizing power could not be improved if thetemperature of the wafers 200 was too low. However, if the throughput isconsidered, as long as oxidizing power can be improved, it may bepreferable that the wafers 200 are kept at the same temperature as instep 1 where HCD gas is supplied. That is, it may be preferable that thetemperature of the heater 207 is set to keep the inside of the processchamber 201 in the same temperature in step 1 and step 3. In this case,the temperature of the heater 207 is set such that the temperature ofthe wafers 200, that is, the inside temperature of the process chamber201 can be kept at a constant temperature in the range from 350° C. to850° C., preferably, in the range from 400° C. to 700° C. in step 1 andstep 3. In addition, it may be preferable that the temperature of theheater 207 is set such that the inside temperature of the processchamber 201 can be kept at the same temperature in step 1 through step 4(described later). In this case, the temperature of the heater 207 isset such that the inside temperature of the process chamber 201 can bekept at a constant temperature in the range from 350° C. to 850° C.,preferably, in the range from 400° C. to 700° C. in step 1 through step4 (described later). In addition, to improve oxidizing power by addingH₂ gas to O₂ gas under a depressurized atmosphere, it is necessary tokeep the inside temperature of the process chamber 201 at 350° C. orhigher, preferably 400° C. or higher, more preferably, 450° C. orhigher. If the inside temperature of the process chamber 201 is kept at400° C. or higher, it is possible to obtain oxidizing power greater thanthat in an O₃ oxidizing treatment performed at 400° C. or higher. If theinside temperature of the process chamber 201 is kept at 450° C. orhigher, it is possible to obtain oxidizing power greater than that in anO₂ plasma oxidizing treatment performed at 450° C. or higher.

By supplying O₂ gas and H₂ gas into the process chamber 201 under theabove-described conditions, the O₂ gas and H₂ gas can be thermallyactivated without using plasma under a heated and depressurizedatmosphere to react with each other, so that an oxidizing speciesincluding oxygen (O) such as atomic oxygen can be produced. Then, thesilicon-containing layers formed on the wafers 200 in step 1 areoxidized mainly by the oxidizing species. By the oxidation, thesilicon-containing layers are changed into silicon oxide layers (SiO₂layers, hereinafter referred to as SiO layers simply). By this oxidizingtreatment, as described above, oxidizing power can be largely increasedas compared with the case where only O₂ gas is supplied. That is, byadding H₂ to O₂ gas under a depressurized atmosphere, oxidizing powercan be largely increased as compared with the case where only O₂ gas issupplied.

Alternatively, at this time, one or both of O₂ gas and H₂ gas may beactivated by plasma. An oxidizing species having more energy can beproduced by supplying O₂ gas and H₂ gas after activating the O₂ gasand/or H₂ gas by plasma, and effects such as improvement in devicecharacteristics can be obtained by performing an oxidizing treatmentusing the oxidizing species. For example, when both of O₂ gas and H₂ gasare activated by plasma, high-frequency power is applied across thefirst rod-shaped electrodes 269 and 270 from the high-frequency powersource 273 through the matching device 272, and then the mixture gas ofthe O₂ gas and H₂ gas supplied into the buffer chamber 237 isplasma-excited as an activated species and is supplied into the processchamber 201 through the gas supply holes 248 c while being exhaustedthrough the exhaust pipe 231. At this time, the high-frequency powerapplied across the first rod-shaped electrode 269 and the secondrod-shaped electrode 270 from the high-frequency power source 273 is setto be in the range of, for example, 50 W to 1,000 W. Other processconditions are set to be the same as those explained in the abovedescription. Furthermore, in the above-described temperature range, O₂gas and H₂ gas can be thermally activated for sufficient reactionnecessary to produce a sufficient amount of oxidizing species. That is,although O₂ gas and H₂ gas are thermally activated without using plasma,sufficient oxidizing power can be obtained. In the case where O₂ gas andH₂ gas are thermally activated and are supplied, soft reaction can becaused, and thus the above-described oxidizing treatment can be softlyperformed.

As well as oxygen (O₂) gas, another gas such as ozone (O₃) gas may beused as an oxygen-containing gas (oxidizing gas). According to anexperiment in which hydrogen-containing gas was added to nitric oxide(NO) gas or nitrous oxide (N₂O) gas in the above-described temperaturerange, oxidizing power was not improved as compared with the case whereonly NO gas or N₂O gas was supplied. That is, it is preferable that gascontaining oxygen but not nitrogen (that is, gas not containing nitrogenbut containing oxygen) is used as an oxygen-containing gas. Ashydrogen-containing gas, not only hydrogen (H₂) gas but also another gassuch as deuterium (D₂) gas may be used. In addition, if gas such asammonia (NH₃) gas or methane (CH₄) gas is used, nitrogen (N) or carbon(C) may permeate into films as an impurity. That is, it is preferablethat gas containing hydrogen but not other elements (that is, gas notcontaining other elements than hydrogen or deuterium) is used as ahydrogen-containing gas. That is, at least one selected from the groupconsisting of O₂ gas and O₃ gas may be used as an oxygen-containing gas,and at least one selected from the group consisting of H₂ gas and D₂ gasmay be used as a hydrogen-containing gas.

[Step 4]

After the silicon-containing layers are changed into silicon oxidelayers, the valve 243 b of the second gas supply pipe 232 b is closed tointerrupt the supply of O₂ gas. In addition, the valve 243 c of thethird gas supply pipe 232 c is closed to interrupt the supply of H₂ gas.At this time, the APC valve 244 of the exhaust pipe 231 is kept open,and the inside of the process chamber 201 is vacuum-evacuated by usingthe vacuum pump 246 so as to remove O₂ gas and H₂ gas remaining in theprocess chamber 201. At this time, if the valves 243 e and 243 f areopened to supply inert gas such as N₂ gas into the process chamber 201,the N₂ gas functions as a purge gas so that O₂ gas or H₂ gas remainingin the process chamber 201 without participating in an reaction or afterparticipating in the formation of the silicon oxide layers can beremoved more efficiently (remaining gas removal).

At this time, the temperature of the heater 207 is set such that thetemperature of the wafers 200 can be in the range from 350° C. to 850°C., preferably, in the range from 400° C. to 700° C. like in the timewhen O₂ gas and H₂ gas are supplied. The supply flow rate of N₂ gasfunctioning as a purge gas is set to be in the range from 200 sccm to1,000 sccm (0.2 slm to 1 slm). Instead of using N2 gas as a purge gas,rare gas such as Ar gas, He gas, Ne gas, and Xe gas may be used as apurge gas.

The above-described step 1 to step 4 are set as one cycle, and the cycleis performed at least once, preferably, a plurality of times, so as toform silicon oxide films (SiO₂ films) on the wafers 200 to apredetermined thickness.

After the silicon oxide films are formed to a predetermined thickness,the valves 243 d, 243 e, and 243 f are opened to supply inert gas suchas N₂ gas into the process chamber 201 through the first inert gassupply pipe 232 d, the second inert gas supply pipe 232 e, and the thirdinert gas supply pipe 232 f while exhausting the N₂ gas through theexhaust pipe 231. The N₂ gas functions as a purge gas. Thus, the insideof the process chamber 201 can be purged with inert gas, and gasremaining in the process chamber 201 can be removed (purge).

Thereafter, the inside of the process chamber 201 is vacuum-evacuated toa desired pressure (vacuum degree) by using the vacuum pump 246. At thistime, the pressure inside the process chamber 201 is measured by thepressure sensor 245, and based on the measured pressure, the APC valve244 is feedback-controlled (pressure adjustment). In addition, theinside of the process chamber 201 is heated to a desired temperature byusing the heater 207. At this time, to obtain desired temperaturedistribution inside the process chamber 201, power to the heater 207 isfeedback-controlled based on temperature information measured by thetemperature sensor 263 (temperature adjustment). In addition, at thistime, the heater 207 is controlled in a manner such that the wafers 200can be kept at a temperature equal to or higher than the temperature ofthe wafers 200 during the film-forming process. The boat 217 (that is,the wafers 200) is continuously rotated by the rotary mechanism 267during the film-forming process. Thereafter, a modification process isperformed to modify the silicon oxide films having a predeterminedthickness formed on the wafers 200.

<Modification Process>

In the modification process, the valve 243 b of the second gas supplypipe 232 b is opened to allow a flow of O₂ gas through the second gassupply pipe 232 b. The flow rate of the O₂ gas flowing through thesecond gas supply pipe 232 b is controlled by the mass flow controller241 b. The O₂ gas adjusted in flow rate is supplied through the gassupply holes 248 b of the second nozzle 233 b into the buffer chamber237 which is heated and depressurized. At the time, the valve 243 c ofthe third gas supply pipe 232 c is also opened so that H₂ gas can flowthrough the third gas supply pipe 232 c. The flow rate of the H₂ gasflowing through the third gas supply pipe 232 c is controlled by themass flow controller 241 c. The H₂ gas adjusted in flow rate is suppliedto the second gas supply pipe 232 b where the H₂ gas is supplied throughthe gas supply holes 248 b of the second nozzle 233 b into the bufferchamber 237 which is heated and depressurized. When the H₂ flows throughthe second gas supply pipe 232 b, the H₂ gas is mixed with the O₂ gas inthe second gas supply pipe 232 b. That is, a mixture gas of the O₂ gasand the H₂ gas is supplied through the second nozzle 233 b. The mixturegas of the O₂ gas and the H₂ gas supplied into the buffer chamber 237 issupplied through the gas supply holes 248 c of the buffer chamber 237into the process chamber 201 which is heated and depressurized, and themixture gas is exhausted through the exhaust pipe 231 (O₂ gas+H₂ gassupply (modification process)).

At this time, the valve 243 e of the second inert gas supply pipe 232 emay be opened to supply an inert gas such as N₂ gas through the secondinert gas supply pipe 232 e. The flow rate of the N2 gas is adjusted bythe mass flow controller 241 e and is supplied into the second gassupply pipe 232 b. In addition, the valve 243 f of the third inert gassupply pipe 232 f may be opened to supply inert gas such as N₂ gasthrough the third inert gas supply pipe 232 f. The flow rate of the N2gas is adjusted by the mass flow controller 241 f and is supplied intothe third gas supply pipe 232 c. At this time, a mixture gas of the O₂gas, H₂ gas, and N₂ gas is supplied through the second nozzle 233 b.Instead of using N₂ gas as inert gas, a rare gas such as Ar gas, He gas,Ne gas, and Xe gas may be used as inert gas.

At this time, the APC valve 244 is properly controlled to keep theinside of the process chamber 201 at a pressure lower than atmosphericpressure, for example, at a pressure ranging from 1 Pa to 1,330 Pa. Theflow rate of the O₂ gas controlled by the mass flow controller 241 b is,for example, in the range from 100 sccm to 10,000 sccm (0.1 slm to 10slm). The flow rate of the H₂ gas controlled by the mass flow controller241 c is, for example, in the range from 100 sccm to 10,000 sccm (0.1slm to 10 slm). In addition, the supply flow rates of the N2 gascontrolled by the mass flow controllers 241 e and 241 f are, forexample, in the range from 0 sccm to 2,000 sccm (0 slm to 2 slm),respectively. In addition, the concentration of the H₂ gas (H₂/(H₂+O₂))is, for example, in the range from 25% to 50%, preferable, in the rangefrom 10% to 33%. That is, for example, it is set such that theproportion of O₂ gas is equal to or greater than the proportion of H₂gas. Preferably, the proportion of O₂ gas is set to be greater than theproportion of H₂ gas. That is, an oxygen-rich condition is made. Thewafers 200 are exposed to the O₂ gas and H₂ gas, for example, for 1minute to 600 minutes. The temperature of the heater 207 is set suchthat the temperature of the wafers 200 can be kept, for example, in therange from 350° C. to 1,200° C. It was ascertained that impurities couldbe removed from films more effectively by adding H₂ gas to O₂ gas undera depressurized atmosphere in the above-mentioned temperature range ascompared with the case where only O₂ gas was supplied (O₂ annealing). Inaddition, it was ascertained that impurities could be removed from filmsmore effectively as compared with the case where only N₂ gas wassupplied at atmospheric pressure (N₂ annealing). For the throughput, itis preferable that the temperature of the heater 207 is set such thatthe temperature of the wafers 200 can be kept in the same temperaturerange in the film-forming process and the modification process. That is,it is preferable that the inside of the process chamber 201 is kept inthe same temperature range in the film-forming process and themodification process. In this case, the temperature of the heater 207 isset such that the temperature of the wafers 200, that is, the insidetemperature of the process chamber 201 can be kept at a constanttemperature in the range from 350° C. to 850° C., preferably, in therange from 400° C. to 700° C. in the film-forming process andmodification process. However, since impurities can be removed from thefilms more effectively by keeping the wafers 200 at a high temperaturein the modification process, it may be more preferable that the wafers200 are kept at a higher temperature in the modification process than inthe film-forming process.

By supplying O₂ gas and H₂ gas into the process chamber 201 under theabove-described conditions, the O₂ gas and H₂ gas can be thermallyactivated without using plasma under a heated and depressurizedatmosphere to react with each other, so that an oxidizing speciesincluding oxygen (O) such as atomic oxygen can be produced. Then, thesilicon oxide films formed on the wafers 200 in the film-forming processare oxidized mainly by the oxidizing species. Then, by this modificationprocess, impurities included in the silicon oxide films are removed. Asdescribed above, the modification process is more effective to removeimpurities from the films as compared with O₂ annealing or N₂ annealing.That is, impurities can be removed from the films more effectively byadding H₂ gas to O₂ gas under a depressurized atmosphere as comparedwith O₂ annealing or N₂ annealing.

Alternatively, at this time, one or both of O₂ gas and H₂ gas may beactivated by plasma. An oxidizing species having more energy can beproduced by supplying O₂ gas and H₂ gas after activating the O₂ gasand/or H₂ gas by plasma, and effects such as improvement in devicecharacteristics can be obtained by performing the modification processusing the oxidizing species. For example, when both of O₂ gas and H₂ gasare activated by plasma, high-frequency power is applied across thefirst rod-shaped electrodes 269 and 270 from the high-frequency powersource 273 through the matching device 272, and then the mixture gas ofthe O₂ gas and H₂ gas supplied into the buffer chamber 237 isplasma-excited as an activated species and is supplied into the processchamber 201 through the gas supply holes 248 c while being exhaustedthrough the exhaust pipe 231. At this time, the high-frequency powerapplied across the first rod-shaped electrode 269 and the secondrod-shaped electrode 270 from the high-frequency power source 273 is setto be in the range of, for example, 50 W to 1,000 W. Other processconditions are set to be the same as those explained in the abovedescription. Furthermore, in the above-described temperature range, O₂gas and H₂ gas can be thermally activated for sufficient reactionnecessary to produce a sufficient amount of oxidizing species. That is,although O₂ gas and H₂ gas are thermally activated without using plasma,sufficient oxidizing power can be obtained. In the case where O2 gas andH2 gas are thermally activated and are supplied, soft reaction can becaused, and thus the above-described modification process can be softlyperformed.

As well as oxygen (O₂) gas, another gas such as ozone (O₃) gas may beused as an oxygen-containing gas (oxidizing gas). According to anexperiment in which hydrogen-containing gas was added to nitric oxide(NO) gas or nitrous oxide (N₂O) gas in the above-described temperaturerange, oxidizing power was not improved as compared with the case whereonly NO gas or N₂O gas was supplied. That is, sufficient impurityremoving effect could not be obtained. That is, it is preferable thatgas containing oxygen but not nitrogen (that is, gas not containingnitrogen but containing oxygen) is used as oxygen-containing gas. Ashydrogen-containing gas, not only hydrogen (H₂) gas but also another gassuch as deuterium (D₂) gas may be used. In addition, if gas such asammonia (NH₃) gas or methane (CH₄) gas is used, nitrogen (N) or carbon(C) may permeate into films as an impurity. That is, it is preferablethat gas containing hydrogen but not other elements (that is, gas notcontaining other elements than hydrogen or deuterium) is used as ahydrogen-containing gas. That is, at least one selected from the groupconsisting of O₂ gas and O₃ gas may be used as an oxygen-containing gas,and at least one selected from the group consisting of H₂ gas and D₂ gasmay be used as a hydrogen-containing gas.

After the modification process is completed, the valves 243 d, 243 e,and 243 f are opened to supply inert gas such as N₂ gas into the processchamber 201 through the first inert gas supply pipe 232 d, the secondinert gas supply pipe 232 e, and the third inert gas supply pipe 232 fwhile exhausting the N₂ gas through the exhaust pipe 231. The N2 gasfunctions as a purge gas. Thus, the inside of the process chamber 201can be purged with inert gas, and gas remaining in the process chamber201 can be removed (purge). Then, the inside atmosphere of the processchamber 201 is replaced with inert gas, and the inside of the processchamber 201 returns to atmospheric pressure (return to atmosphericpressure).

Thereafter, the boat elevator 115 lowers the seal cap 219 to open thebottom side of the reaction tube 203 and unload the boat 217 in whichthe processed wafers 200 are held to the outside of the reaction tube203 through the bottom side of the reaction tube 203 (boat unloading).Then, the processed wafers 200 are discharged from the boat 217 (waferdischarging).

In the modification process of the current embodiment, O₂ gas and H₂ gasare allowed to react with each other under a heated and depressurizedatmosphere to produce an oxidizing species containing oxygen (O) such asatomic oxygen, and the silicon oxide films (SiO₂ films) are modified byusing the oxidizing species. Since the energy of the oxidizing speciesis greater than the bond energy of Si—N, Si—Cl, Si—H, and Si—C bonds ofthe silicon oxide films, the Si—N, Si—Cl, Si—H, and Si—C bonds of thesilicon oxide films can be broken by giving the energy of the oxidizingspecies to the silicon oxide films (objects of oxidizing treatment). N,H, Cl, and C separated from Si are removed from the films are dischargedin the form of N₂, H₂, Cl₂, HCl, CO₂, etc. In addition, Si bondingelectrons remaining after N, H, Cl, and C are separated is coupled withO included in the oxidizing species, thereby forming Si—O bonds. Inaddition, at this time, the silicon oxide films are densified. In thisway, the silicon oxide films are modified. It was ascertained that theSiO₂ films formed by the process sequence of the current embodiment hadvery low nitrogen, hydrogen, chlorine, and carbon concentrations and theratio of Si/O of the SiO₂ film was very close to a stoichiometriccomposition ratio, 0.5. That is, high-quality films could be formed.

In step 3 of the film-forming process of the current embodiment, O₂ gasand H₂ gas are allowed to react with each other under a heated anddepressurized atmosphere to produce an oxidizing species containingoxygen (O) such as atomic oxygen. By using the oxidizing species, thesilicon-containing layers (Si layers or HCD gas adsorption layers) arechanged into silicon oxide layers (SiO layers). Since the energy of theoxidizing species is greater than the bond energy of Si—N, Si—Cl, Si—H,and Si—C bonds of the silicon-containing layers, the Si—N, Si—Cl, Si—H,and Si—C bonds of the silicon-containing layers can be broken by givingthe energy of the oxidizing species to the silicon-containing layers(objects of oxidizing treatment). N, H, Cl, and C separated from Si areremoved from the layers are discharged in the form of N₂, H₂, Cl₂, HCl,CO₂, etc. In addition, Si bonding electrons remaining after N, H, Cl,and C are separated is coupled with O included in the oxidizing species,thereby forming Si—O bonds. In this way, the silicon-containing layersare changed into silicon oxide layers by oxidation. That is, accordingto the current embodiment, the same impurity removing effect as that ofthe modification process can be obtained in the oxidizing treatment(step 3) of the film-forming process. Thus, according to the currentembodiment, silicon oxide films having low nitrogen, hydrogen, chlorine,and carbon concentrations can be obtained. Then, by performing themodification process of the current embodiment to the silicon oxidefilms formed as described above, the nitrogen, hydrogen, chlorine, andcarbon concentrations of the silicon oxide films can be further reduced,and thus high-quality oxide films having very low impurityconcentrations can be obtained.

In this way, according to the current embodiment, silicon oxide filmshaving low impurity concentrations are formed in the film-formingprocess, and modification treatment is performed to the silicon oxidefilms having low impurity concentrations in the modification process soas to further lower the impurity concentrations of the silicon oxidefilms. That is, according to the current embodiment, the impurityconcentrations of the films are reduced in two steps: the impurityremoving action in the oxidizing treatment (step 3) of the film-formingprocess, and the impurity removing action in the modification process.

In the current embodiment, process conditions of the oxidizing treatment(step 3) of the film-forming process may be set such thatsilicon-containing layers each constituted by less than one atomic layerto several atomic layers can be oxidized. Under these processconditions, the above-described impurity removing action can occur.Furthermore, in the current embodiment, process conditions of themodification process may be set such that modification treatment can beperformed to silicon oxide films. That is, process conditions of themodification process may be set such that impurities can be removed fromsilicon oxide films more efficiently. In addition, it is known that theimpurity removing action of the modification process occurs morevigorously as the temperature of substrates is increased and the supplytimes of gases are increased. Therefore, it is preferable that thetemperature of substrates in the modification process is set to behigher than the temperature of the substrates in the oxidizing treatment(step 3) of the film-forming process or the supply times of gases in themodification process are set to be longer than the supply times of gasesin the oxidizing treatment (step 3) of the film-forming process.

In addition, since it is known that the action of removing impuritiesfrom films is affected more strongly by the temperature of substratesthan the supply times of gases in the modification process, setting thetemperature of substrates to a high value is more preferable thansetting the supply times of gases to long periods in the modificationprocess to improve the efficiency of impurity removing action in themodification process.

In addition, it was ascertained that if a silicon oxide film was formedaccording to the process sequence of the current embodiment, the filmthickness uniformity in a surface of a wafer could be improved ascompared with the case where a silicon oxide film was formed accordingto a general CVD method. In a general CVD method, inorganic sources suchas DCS and N₂O are simultaneously supplied to form a silicon oxide film(HTO (higher temperature oxide) film) by chemical vapor deposition(CVD). In addition, it was ascertained that the impurity concentrationssuch as hydrogen and chlorine concentrations of a silicon oxide filmformed by the process sequence of the current embodiment were much lowerthan those of a silicon oxide film formed by a general CVD method. Inaddition, it was ascertained that the impurity concentrations of asilicon oxide film formed by the process sequence of the currentembodiment were much lower than those of a silicon oxide film formed bya CVD method using an organic silicon source. In addition, according tothe process sequence of the current embodiment, although an organicsilicon source was used, the film thickness uniformity in a surface of awafer and the impurity concentrations of a film were satisfactory.

In the current embodiment, O₂ gas and H₂ gas are supplied from the samesecond nozzle 233 b into the process chamber 201 through the bufferchamber 237, and the second nozzle 233 b and the buffer chamber 237 areheated to the same temperature as the process chamber 201. Therefore,the O₂ gas and H₂ gas react with each other in the second nozzle 233 band the buffer chamber 237 which are heated and kept at a pressure lowerthan atmospheric pressure, and thus an oxidizing species containingoxygen is generated in the second nozzle 233 b and the buffer chamber237. In addition, the insides of the second nozzle 233 b and the bufferchamber 237 are kept at a pressure higher than the inside pressure ofthe process chamber 201. This facilitates the reaction between the O₂gas and H₂ gas in the second nozzle 233 b and the buffer chamber 237,and thus a more amount of oxidizing species can be generated by thereaction between the O₂ gas and H₂ gas. As a result, oxidizing power canbe increased, and impurities can be removed from films more effectively.In addition, since the O₂ gas and H₂ gas can be mixed with each othermore uniformly in the second nozzle 233 b and the buffer chamber 237before being supplied into the process chamber 201, the O₂ gas and H₂gas can react with each other more uniformly to produce an oxidizingspecies having a uniform concentration. As a result, oxidizing power canbe uniformly applied among the wafers 200, and impurity removing effectcan be uniform among the wafers 200. As described above, since O₂ gasand H₂ gas are supplied into the process chamber 201 through the samenozzle, oxidizing power can be increased much more, and the uniformityof the oxidizing power can be improved much more. In addition, impurityremoving effect can be improved much more, and the uniformity ofimpurity removing effect can be improved much more. If plasma is used,the buffer chamber 237 may not be provided. However, the same effects asthose described above can be obtained because O₂ gas and H₂ gas aremixed in the same nozzle 233 b and supplied into the process chamber 201from the same nozzle 233 b.

In the case where O₂ gas and H₂ gas are supplied from the same secondnozzle 233 b into the process chamber 201 through the buffer chamber237, although a more amount of oxidizing species can be produced in thesecond nozzle 233 b and the buffer chamber 237, the oxidizing speciesmay be deactivated while passing through the second nozzle 233 b and thebuffer chamber 237, and thus the amount of oxidizing species reachingthe wafers 200 may be decreased. However, if O₂ gas and H₂ gas aresupplied into the process chamber 201 from different nozzles, the O₂ gasand H₂ gas start to mix with each other in the process chamber 201, andthus an oxidizing species is generated in the process chamber 201 sothat it may be possible to prevent the oxidizing species from beingdeactivated in the second nozzle 233 b or the buffer chamber 237.

In the film-forming process of the current embodiment, H₂ gas which is ahydrogen-containing is intermittently supplied as shown in FIG. 4. Thatis, explanation has been given on an exemplary case where H₂ is suppliedonly in step 3. However, H₂ gas may be continuously supplied. That is,H₂ gas may be continuously supplied while step 1 to step 4 are repeated.Alternatively, H₂ gas may be intermittently supplied in step 1 and step3 or in step 1 to step 3. Alternatively, H₂ gas may be supplied in step2 and step 3 or in step 3 and step 4.

According to the current embodiment, in step 1 of the film-formingprocess, that is, when HCD gas is supplied, H₂ gas may be supplied toextract Cl from the HCD gas and thus to increase the film-forming rateand reduce the Cl impurity concentration of films. Furthermore, in step2, that is, after the supply of HCD gas is stopped, H₂ gas may besupplied before O₂ gas is supplied, for effectively controlling filmthickness uniformity. Furthermore, in step 2, by supplying H₂ gas priorto supply of O₂ gas, for example, an oxide film may be formed on partswhere metal and silicon are exposed in a manner such that the oxide filmis uniformly laid on the metal and silicon without oxidizing the metal.Furthermore, in step 4, that is, after supply of O₂ is stopped butsupply of HCD gas is not started, H₂ gas may be supplied to terminatethe surfaces of SiO layers formed in step 3 with hydrogen so that HCDgas supplied in the next step 1 can be easily adsorbed on the surfacesof the SiO layers.

Furthermore, in the film-forming process of the above-describedembodiment, step 1, step 2, step 3, and step 4 are sequentiallyperformed. Step 1, step 2, step 3, and step 4 are set as one cycle, andthe cycle is performed at least once, preferably, a plurality of times,to form silicon oxide films having a predetermined thickness on thewafers 200. Unlike this, the order of step 1 and step 3 may be changed.That is, step 3, step 2, step 1, and step 4 may be sequentiallyperformed. Step 3, step 2, step 1, and step 4 may be set as one cycle,and the cycle may be performed at least once, preferably, a plurality oftimes, so as to form silicon oxide films on the wafers 200 to apredetermined thickness.

Furthermore, according to the above-described embodiment, in step 3 ofthe film-forming process, silicon-containing layers are changed intosilicon oxide layers by using O₂ gas and H₂ gas as an oxidant. However,an oxygen-containing gas such as O₂ gas, O₃ gas, or H₂O gas may be usedalone as an oxidant, or an oxygen-containing gas activated by plasma maybe used as an oxidant. For example, a gas obtained by activating O₂ gasby plasma may be used. The same effects as those described above can beobtained by modifying oxide films formed in this way through themodification process of the above-described embodiment.

Furthermore, in the above-described embodiment, silicon oxide films(SiO₂ films) containing semiconductor silicon (Si) are formed onsubstrates as oxide films. However, the present invention may be appliedto other cases where metal oxide films containing a metal element suchas zirconium (Zr), hafnium (Hf), titanium (Ti), or aluminium (Al) areformed on substrates as oxide films. In this case, formation of layerscontaining a metal element on substrates by supplying a source gas (step1); removal of remaining gas by purge (step 2); changing the layerscontaining a metal element into metal oxide layers by supplying anoxidant (step 3); and removal of remaining gas by purge (step 4) are setas one cycle, and the cycle is performed at least once, preferably, aplurality of times, to form metal oxide films having a predeterminedthickness on the substrates. In a modification process, while keepingthe substrates under a heated condition at a pressure lower thanatmospheric pressure, an oxygen-containing gas and a hydrogen-containinggas are supplied to the substrates on which the metal oxide films areformed, so as to modify the metal oxide films.

For example, zirconium oxide films (ZrO₂ films) may be formed onsubstrates as metal oxide films containing zirconium (Zr) in thefollowing manner. In a film-forming process, formation ofzirconium-containing layers on substrates by supplying a source gas(step 1); removal of remaining gas by purge (step 2); changing thezirconium-containing layers into zirconium oxide layers by supplying anoxidant (step 3); and removal of remaining gas by purge (step 4) are setas one cycle, and the cycle is performed at least once, preferably, aplurality of times, to form zirconium oxide films having a predeterminedthickness on the substrates. In a modification process, while keepingthe substrates under a heated condition at a pressure lower thanatmospheric pressure, an oxygen-containing gas and a hydrogen-containinggas are supplied to the substrates on which the zirconium oxide filmsare formed, so as to modify the zirconium oxide films. In step 1, forexample, TEMAZ (tetrakis(ethylmethylamino)zirconium: Zr[N(C₂H₅) (CH₃)]₄)gas may be used as the source gas. In step 3, an oxygen-containing gasand a hydrogen-containing gas may be used as the oxidant like in theabove-described embodiment. Gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In addition, as the oxidant, anoxygen-containing gas such as O₂ gas, O₃ gas, or H₂O gas may be usedalone, or an oxygen-containing gas activated by plasma may be used. Forexample, a gas obtained by activating O₂ gas by plasma may be used. Inthe modification process, gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In this case, the first gas supply system(source gas supply system) of the substrate processing apparatus of theabove-described embodiment may be configured as a zirconium-containinggas supply system. Process conditions of the film-forming process andthe modification process may be set within the process condition rangesof the above-described embodiment. In this case, gases may be suppliedas shown in FIG. 5. FIG. 5 is a view illustrating gas supply timing of aprocess sequence for the case where the present invention is applied toformation of zirconium oxide films on substrates as metal oxide films.FIG. 5 illustrates an exemplary case where TEMAZ gas is used as a sourcegas, O₂ gas is used as an oxygen-containing gas, H₂ gas is used as ahydrogen-containing gas, and N₂ gas is used as a purge gas.

In addition, for example, hafnium oxide films (HfO₂ films) may be formedon substrates as metal oxide films containing hafnium (Hf) in thefollowing manner. In a film-forming process, formation ofhafnium-containing layers on substrates by supplying a source gas (step1); removal of remaining gas by purge (step 2); changing thezirconium-containing layers into hafnium oxide layers by supplying anoxidant (step 3); and removal of remaining gas by purge (step 4) are setas one cycle, and the cycle is performed at least once, preferably, aplurality of times, to form hafnium oxide films having a predeterminedthickness on the substrates. In a modification process, while keepingthe substrates under a heated condition at a pressure lower thanatmospheric pressure, an oxygen-containing gas and a hydrogen-containinggas are supplied to the substrates on which the hafnium oxide films areformed, so as to modify the hafnium oxide films. In step 1, TEMAH(tetrakis(ethylmethylamino)hafnium: Hf[N(C₂H₅)(CH₃)]₄) gas or TDMAH(tetrakis(dimethylamino)hafnium: Hf[N(CH₃)₂]₄) gas may be used as thesource gas. In step 3, an oxygen-containing gas and ahydrogen-containing gas may be used as the oxidant like in theabove-described embodiment. Gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In addition, as the oxidant, anoxygen-containing gas such as O₂ gas, O₃ gas, or H₂O gas may be usedalone, or an oxygen-containing gas activated by plasma may be used. Forexample, a gas obtained by activating O₂ gas by plasma may be used. Inthe modification process, gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In this case, the first gas supply system(source gas supply system) of the substrate processing apparatus of theabove-described embodiment may be configured as a hafnium-containing gassupply system. Process conditions of the film-forming process and themodification process may be set within the process condition ranges ofthe above-described embodiment.

In addition, for example, titanium oxide films (TiO₂ films) may beformed on substrates as metal oxide films containing titanium (Ti) inthe following manner. In a film-forming process, formation oftitanium-containing layers on substrates by supplying a source gas (step1); removal of remaining gas by purge (step 2); changing thetitanium-containing layers into titanium oxide layers by supplying anoxidant (step 3); and removal of remaining gas by purge (step 4) are setas one cycle, and the cycle is performed at least once, preferably, aplurality of times, to form titanium oxide films having a predeterminedthickness on the substrates. In a modification process, while keepingthe substrates under a heated condition at a pressure lower thanatmospheric pressure, an oxygen-containing gas and a hydrogen-containinggas are supplied to the substrates on which the titanium oxide films areformed, so as to modify the titanium oxide films. In step 1, forexample, TiCl₄ (titanium tetrachloride) gas or TDMAT(tetrakis(dimethylamino)titanium: Ti[N(CH₃)₂]₄) gas may be used as thesource gas. In step 3, an oxygen-containing gas and ahydrogen-containing gas may be used as the oxidant like in theabove-described embodiment. Gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In addition, as the oxidant, anoxygen-containing gas such as O₂ gas, O₃ gas, or H₂O gas may be usedalone, or an oxygen-containing gas activated by plasma may be used. Forexample, a gas obtained by activating O₂ gas by plasma may be used. Inthe modification process, gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In this case, the first gas supply system(source gas supply system) of the substrate processing apparatus of theabove-described embodiment may be configured as a titanium-containinggas supply system. Process conditions of the film-forming process andthe modification process may be set within the process condition rangesof the above-described embodiment.

In addition, for example, aluminium oxide films (Al₂O₃ films) may beformed on substrates as metal oxide films containing aluminium (Al) inthe following manner. In a film-forming process, formation ofaluminium-containing layers on substrates by supplying a source gas(step 1); removal of remaining gas by purge (step 2); changing thealuminium-containing layers into aluminium oxide layers by supplying anoxidant (step 3); and removal of remaining gas by purge (step 4) are setas one cycle, and the cycle is performed at least once, preferably, aplurality of times, to form aluminium oxide films having a predeterminedthickness on the substrates. In a modification process, while keepingthe substrates under a heated condition at a pressure lower thanatmospheric pressure, an oxygen-containing gas and a hydrogen-containinggas are supplied to the substrates on which the aluminium oxide filmsare formed, so as to modify the aluminium oxide films. In step 1, TMA(trimethyl-aluminium: Al(CH₃)₃) gas may be used as a source gas. In step3, an oxygen-containing gas and a hydrogen-containing gas may be used asthe oxidant like in the above-described embodiment. Gases exemplified inthe above-described embodiments may be used as the oxygen-containing gasand the hydrogen-containing gas. In addition, as the oxidant, anoxygen-containing gas such as O₂ gas, O₃ gas, or H₂O gas may be usedalone, or an oxygen-containing gas activated by plasma may be used. Forexample, a gas obtained by activating O₂ gas by plasma may be used. Inthe modification process, gases exemplified in the above-describedembodiments may be used as the oxygen-containing gas and thehydrogen-containing gas. In this case, the first gas supply system(source gas supply system) of the substrate processing apparatus of theabove-described embodiment may be configured as an aluminium-containinggas supply system. Process conditions of the film-forming process andthe modification process may be set within the process condition rangesof the above-described embodiment.

It was ascertained that application of the present invention toformation of metal oxide films resulted in the same effects as thoseobtained in the case where the present invention was applied toformation of silicon oxide films. Impurity removing effects wereascertained as follows. When the present invention was applied toformation of silicon oxide films, impurity concentrations of the siliconoxide films, particularly, H concentration and Cl concentration werereduced, and when the present invention was applied to formation ofmetal oxide films, impurity concentrations of the metal oxide films,particularly, H concentration, Cl concentration, C concentration, and Nconcentration were reduced. In addition, silicon oxide films formedthrough the film-forming process of the current embodiment have very lowimpurity concentrations, particularly, C concentration and Hconcentration although the modification process is not performed. Thismay be because C and N are not included in the source gas.

As described above, the process sequence of the current embodiment canbe applied to a process of forming a metal oxide (that is, a metal oxidefilm) such as a high permittivity insulating film (high-k film) on asubstrate as well as a process of forming a silicon oxide film on asubstrate. That is, the process sequence of the current embodiment canbe applied to the case where a predetermined element included in anoxide film is a metal element as well as the case where thepredetermined element is a semiconductor element.

In the film-forming process of the above-described embodiment, oxidefilms are cyclically formed by alternately repeating a process ofsupplying a source gas into the process vessel; and a process ofsupplying an oxygen-containing gas and a hydrogen-containing gas intothe process vessel which is heated and kept at a pressure lower thanatmospheric pressure. However, the present invention is not limited tothe oxide film forming method. For example, a source gas and anoxygen-containing gas may be simultaneously supplied into the processvessel to form oxide films according to a general CVD or metal organicchemical vapor deposition (MOCVD) method. For example, SiH₄ gas and O₂gas may be simultaneously supplied into the process vessel to form SiO₂films (low temperature oxide (LTO) films) as oxide films by a CVDmethod. In addition, for example, TDMAH gas and O₂ gas may besimultaneously supplied into the process vessel to form HfO₂ films asoxide films by an MOCVD method. The same effects as those describedabove can be obtained by modifying the CVD/MOCVD oxide films formed inthis way through the modification process of the above-describedembodiment.

In the above-described embodiment, the film-forming process and themodification process are performed in the same process vessel. However,alternatively, the film-forming process and the modification process maybe separately performed in different process vessels.

Furthermore, in the above-described embodiment, the modification processis performed after performing the film-forming process. However,alternatively, the modification process may be performed while thefilm-forming process is performed as shown in FIG. 9. That is, afilm-forming process of forming silicon oxide films (silicon oxidelayers) thinner than silicon oxide films to be finally formed, and amodification process may be alternately repeated. For example, amodification process may be performed each time a cycle of step 1 tostep 4 is performed ten times in a film-forming process. In the exampleshown in FIG. 9, a modification process is performed each time a cycleof step 1 to step 4 is performed three times in a film-forming process.In the example show in FIG. 9, at each cycle where the modificationprocess is performed (the third and sixth cycles), oxidizing treatment(step 3) to silicon-containing layers, and modification treatment tosilicon oxide layers formed by that time are continuously performed.Alternatively, at each cycle where the modification process isperformed, oxidizing treatment (step 3) to silicon-containing layers andmodification treatment to silicon oxide layers formed by that time maybe intermittently performed by inserting a purge process between theoxidizing treatment and the modification treatment.

In this way, a film-forming process of forming silicon oxide films(silicon oxide layers) thinner than silicon oxide films to be finallyformed, and a modification process are alternately repeated. That is,the modification process can be performed to silicon oxide layers havinga relatively thin thickness, and thus the effect of removing impuritiesfrom films can be further improved. This method is particularlyeffective for the case of forming silicon oxide films the finalthickness of which is relatively large in the range of 200 Å to 300 Å ormore.

EXAMPLES First Example

Next, a first example will be described.

SiO₂ films were formed on wafers at 450° C. and 600° C. through thefilm-forming process of the above-described embodiment. Thereafter, someof the SiO₂ films formed at 450° C. were modified at 450° C. and 600° C.under a depressurized condition by using O₂ gas and H₂ gas (themodification treatment of the above-described embodiment), and the otherof the SiO₂ films formed on the wafers at 450° C. were annealed at 450°C. and 600° C. under atmospheric pressure by using N₂ gas (modificationtreatment of comparative example). Before and after the modificationtreatments, the SiO₂ films were etched by using a 1% hydrofluoric acid(HF) solution, and wafer etching rates (hereinafter also referred asWERs) of the SiO₂ films were measured. Specifically, the following sixevaluation samples were prepared, and the WERs of SiO₂ films of theevaluation samples were measured by using a 1% HF solution. Except fortemperature conditions (wafer temperature conditions), other processconditions used for preparing the evaluation samples were set in theprocess condition ranges described in the above embodiment.

(A) Evaluation sample prepared by forming a SiO₂ film at 600° C. throughthe film-forming process of the embodiment of the present invention.

(B) Evaluation sample prepared by forming a SiO₂ film at 450° C. throughthe film-forming process of the embodiment of the present invention.

(C) Evaluation sample prepared by: forming a SiO₂ film at 450° C.through the film-forming process of the embodiment of the presentinvention, and annealing the SiO₂ film by using N₂ under atmosphericpressure at 600° C. higher than the film-forming temperature(modification treatment of comparative example).

(D) Evaluation sample prepared by: forming a SiO₂ film at 450° C.through the film-forming process of the embodiment of the presentinvention, and modifying the SiO₂ film by O₂ gas and H₂ gas under adepressurized condition at 600° C. higher than the film-formingtemperature (modification treatment of the embodiment of the presentinvention).

(E) Evaluation sample prepared by: forming a SiO₂ film at 450° C.through the film-forming process of the embodiment of the presentinvention, and annealing the SiO₂ film by using N₂ under atmosphericpressure at 450° C. equal to the film-forming temperature (modificationtreatment of comparative example).

(F) Evaluation sample prepared by: forming a SiO₂ film at 450° C.through the film-forming process of the embodiment of the presentinvention, and modifying the SiO₂ film by O₂ gas and H₂ gas under adepressurized condition at 450° C. equal to the film-forming temperature(modification treatment of the embodiment of the present invention).

The results are shown in FIG. 6. FIG. 6 is a view showing therelationship between main process conditions of the evaluation samplesand wafer etching rates (WERs) of the SiO₂ films of the evaluationsamples. In FIG. 6, the horizontal axis denotes main process conditionsof the evaluation samples, and the vertical axis denotes WERs of theSiO₂ films of the evaluation samples. In FIG. 6, relative WERs are shownbased on WER of the SiO₂ film of the evaluation sample (B) formed at450° C. (that is, relatively WERs when the WER of the SiO₂ film of theevaluation sample (B) is 1). In the current example, film quality isevaluated by WERs. That is, in the current example, it is determinedthat a lower WER means better film quality. Herein, a good-quality filmmeans a dense film having low impurity concentrations. For example, inthe case where a large amount of impurity such as Cl is contained in afilm, since the impurity such as Cl is easily ionized by an HF solution,the WER of the film is high. However, in the case where a small amountof impurity such as Cl is contained in a film, the WER of the film islow. Although it is assumed that the same molecular amounts of dense andrough films are dissolved per unit time when the dense and rough filmsare immersed in an HF solution, since the molecular density of the densefilm is greater than the rough film, the dense film is less reduced inthickness, and thus the WER of the dense film is low. Therefore, it canbe considered that a film having a low WER is a high-quality film whichis dense and has less impurity.

As shown in FIG. 6, the WER of the SiO₂ film of the evaluation sample(A) formed at 600° C. is 0.75 which is lower than the WER of the SiO₂film of the evaluation sample (B) formed at 450° C. Thus, the SiO₂ filmof the evaluation sample (A) may be considered to be satisfactory inquality. The WER of the SiO₂ film of the evaluation sample (C) formed at450° C. and annealed by N₂ at 600° C. is 0.84 which is lower than theWER of the SiO₂ film of the evaluation sample (B) formed at 450° C. andnot annealed by N₂. That is, it can be understood that the quality ofthe SiO₂ film of the evaluation sample (C) is improved. In addition, theWER of the SiO₂ film of the evaluation sample (D), which is formed at450° C. and modified at 600° C. under a depressurized condition by usingO₂ gas+H₂ gas, is further reduced to 0.72. That is, it can be understoodthat the quality of the SiO₂ film of the evaluation sample (D) isfurther improved. In addition, the WER of the SiO₂ film of theevaluation sample (D) is lower than the WER of the SiO₂ film of theevaluation sample (A) formed at 600° C. That is, it can be understoodthat the quality of the SiO₂ film of the evaluation sample (D) is mostimproved. The N₂ annealing of the evaluation sample (C), and themodification treatment of the evaluation sample (D) under adepressurized condition using O₂ gas+H₂ gas were performed for the sameprocess time (process times were set to be equal), but it could beunderstood that the film quality improvement effect was greater in thecase of the modification treatment performed under a depressurizedcondition using O₂ gas+H₂ gas than in the case of the N₂ annealing. Thatis, a dense film having less impurity could be obtained in the case ofthe modification treatment performed under a depressurized conditionusing O₂ gas and H₂ gas rather than in the case of the N₂ annealing.

As it can be understood from FIG. 6, if an oxide film is formed at arelatively high temperature, the impurity concentration of the oxidefilm can be reduced. However, in a high temperature region, a source gasis thermally decomposed and an etching action is caused by HCl and Cl₂generated from the source gas. Therefore, it is difficult to ensure thein-surface thickness uniformity of an oxide film. However, if an oxidefilm is formed at a relatively low temperature, the in-surface thicknessuniformity of the oxide film can be satisfactory. However, if an oxidefilm is formed at a low temperature, the impurity concentration of theoxide film is high. However, according to the present invention, anoxide film is formed at a relatively low temperature for good in-surfacefilm thickness uniformity, and then a modification treatment isperformed at a relatively high temperature under a depressurizedcondition by using O₂ gas+H₂ gas, so as to remove a disadvantage of theoxide film formed at a low temperature (a relatively large amount ofimpurity in the oxide film). Thus, the quality of the oxide film can besatisfactory. In addition, owing to the oxide film having satisfactoryquality, electric characteristics can be improved.

Furthermore, in the evaluation sample (E) formed at 450° C. and annealedby N₂ at 450° C., the WER of the SiO₂ film is improved to 0.98 althoughthe improvement is small. In addition, the WER of the SiO₂ film of theevaluation sample (F), which is formed at 450° C. and modified at 450°C. under a depressurized condition by using O₂ gas+H₂ gas, is improvedto 0.97 although the improvement is small. That is, although an N₂annealing treatment or a modification treatment under a depressurizedcondition using O₂ gas+H₂ gas is performed at the same temperature asthe temperature of a film-forming process, film quality can be improved.For example, by performing the modification treatment for a longer time,the same effects can be obtained as the effects that can be obtained byperforming an N₂ annealing treatment at a temperature higher than thetemperature of a film-forming process or a modification treatment undera depressurized condition using O₂ gas+H₂ gas at a temperature higherthan the temperature of a film-forming process. At this time, that is,when an N₂ annealing treatment or a modification treatment under adepressurized condition using O₂ gas+H₂ gas is performed at the sametemperature as the temperature of a film-forming process, more filmquality improvement effect can be obtained in the case of themodification treatment under a depressurized condition using O₂ gas+H₂gas than in the case of the N₂ annealing treatment.

That is, film quality improvement effect is greater in the case ofperforming a modification treatment to an oxide film under adepressurized condition using O₂ gas+H₂ gas at a temperature equal to orhigher than the temperature of a film-forming process, than in the caseof performing an N₂ annealing treatment to the oxide film at the sametemperature as the modification treatment. Sometimes the thickness of afilm was slightly increased after a modification treatment was performedunder a depressurized condition using O₂ gas+H₂ gas. However, the amountof such film thickness increase could be kept close to zero bycontrolling process conditions of the modification treatment. That is,by controlling process conditions of a modification treatment, anunderlayer material could be minimally consumed.

Second Example

Next, a second example will be described.

SiO₂ films were formed on wafers at 450° C., 600° C., and 700° C.through the film-forming process of the above-described embodiment.Thereafter, the SiO₂ films formed at 450° C. and 600° C. were modifiedat 700° C. under a depressurized condition by using O₂ gas and H₂ gas(the modification treatment of the above-described embodiment) for 60minutes. Before and after the modification treatment, impurityconcentrations (H, Cl) of the SiO₂ films were measured. Specifically,the following five evaluation samples were prepared, and impurityconcentrations (H, Cl) of SiO₂ films of the evaluation samples weremeasured. Except for temperature conditions (wafer temperatureconditions), other process conditions used for preparing the evaluationsamples were set in the process condition ranges described in the aboveembodiment. In addition, the impurity concentrations of the films weremeasured by a secondary ion mass spectrometer (SIMS).

(A) Evaluation sample prepared by forming a SiO₂ film at 450° C. throughthe film-forming process of the embodiment of the present invention.

(B) Evaluation sample prepared by forming a SiO₂ film at 600° C. throughthe film-forming process of the embodiment of the present invention.

(C) Evaluation sample prepared by forming a SiO₂ film at 700° C. throughthe film-forming process of the embodiment of the present invention.

(D) Evaluation sample prepared by: forming a SiO₂ film at 450° C.through the film-forming process of the embodiment of the presentinvention, and modifying the SiO₂ film by O₂ gas and H₂ gas under adepressurized condition at 700° C. higher than the film-formingtemperature (modification treatment of the embodiment of the presentinvention).

(E) Evaluation sample prepared by: forming a SiO2 film at 600° C.through the film-forming process of the embodiment of the presentinvention, and modifying the SiO₂ film by O₂ gas and H₂ gas under adepressurized condition at 700° C. higher than the film-formingtemperature (modification treatment of the embodiment of the presentinvention).

The results are shown in FIG. 7 and FIG. 8. FIG. 7 shows the impurity(H) concentrations of the SiO₂ films of the evaluation samples. FIG. 8shows the impurity (Cl) concentrations of the SiO₂ films of theevaluation samples. In FIG. 7 and FIG. 8, the horizontal axes denote thedepth (nm) from a surface of a SiO₂ film, and the vertical axes denoteimpurity (H, Cl) concentrations (atoms/cm³).

Referring to FIG. 7 and FIG. 8, the H concentration and Cl concentrationof the SiO₂ film of the evaluation sample (D) formed at 450° C. andmodified at 700° C. are much lower than the H concentration and Clconcentration of the SiO₂ film of the evaluation sample (A) formed at450° C. but not modified. That is, it can be understood that the qualityof the SiO₂ film of the evaluation sample (D) is largely improved. Inaddition, the H concentration and Cl concentration of the (E) formed at600° C. and modified at 700° C. are much lower than the H concentrationand Cl concentration of the SiO₂ film of the evaluation sample (B)formed at 600° C. but not modified. That is, it can be understood thatthe quality of the SiO₂ film of the evaluation sample (E) is largelyimproved. In addition, as shown in FIG. 7, although the H concentrationof the SiO₂ film of the evaluation sample (E) formed at 600° C. andmodified at 700° C. is similar to the H concentration of the SiO₂ filmof the evaluation sample (C) formed at 700° C., the H concentration ofthe SiO₂ film of the evaluation sample (D) formed at 450° C. andmodified at 700° C. is lower than the H concentration of the evaluationsample (C) formed at 700° C. The H concentration of the evaluationsample (D) is lowest.

According to the present invention, the quality of an oxide film can beimproved while avoiding risks of a high temperature oxide film formingprocess, to improve electric characteristics. In addition, when an oxidefilm is formed, consumption of an under-layer material can be minimizedto make the oxide film suitable for constructing a fine structure.

The present invention also includes the following preferred embodiments.

According to an embodiment of the present invention, there is provided amethod of manufacturing a semiconductor device, including:

(a) forming an oxide film having a predetermined thickness on asubstrate by alternately repeating: (a-1) forming a layer containing apredetermined element on the substrate by supplying a source gascontaining the predetermined element into a process vessel accommodatingthe substrate and exhausting the source gas from the process vessel; and(a-2) changing the layer containing the predetermined element into anoxide layer by supplying an oxygen-containing gas and anhydrogen-containing gas into the process vessel, wherein an inside ofthe process vessel is under a heated atmosphere having a pressure lowerthan an atmospheric pressure, and exhausting the oxygen-containing gasand the hydrogen-containing gas from the process vessel; and

(b) modifying the oxide film formed on the substrate by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under the heatedatmosphere having the pressure lower than the atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel.

Preferably, a temperature of the substrate in the step (b) is higherthan a temperature of the substrate in the step (a-2); or a gas supplytime of each of the gases in the step (b) is longer than a gas supplytime of each of the gases in the step (a-2).

Preferably, a temperature of the substrate in the step (b) is higherthan a temperature of the substrate in the step (a).

Preferably, the step (a) and the step (b) are alternately repeated.

Preferably, in the step (a-2), the oxygen-containing gas is reacted withthe hydrogen-containing gas under the heated atmosphere having thepressure lower than the atmospheric pressure to form an oxidizingspecies, and the layer containing the predetermined element is changedinto the oxide layer by using the oxidizing species, and

in the step (b), the oxygen-containing gas is reacted with thehydrogen-containing gas under the heated atmosphere having the pressurelower than the atmospheric pressure to form the oxidizing species, andthe oxide film is modified using the oxidizing species.

According to another embodiment of the present invention, there isprovided a method of manufacturing a semiconductor device, including:

(a) forming a silicon oxide film having a predetermined thickness on asubstrate by alternately repeating: (a-1) forming a silicon-containinglayer on the substrate by supplying a source gas containing a siliconinto a process vessel accommodating the substrate and exhausting thesource gas from the process vessel; and (a-2) changing thesilicon-containing layer into a silicon oxide layer by supplying anoxygen-containing gas and an hydrogen-containing gas into the processvessel, wherein an inside of the process vessel is under a heatedatmosphere having a pressure lower than an atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel; and

(b) modifying the oxide film formed on the substrate by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under the heatedatmosphere having the pressure lower than the atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel.

Preferably, a temperature of the substrate in the step (b) is higherthan a temperature of the substrate in the step (a-2); or a gas supplytime of each of the gases in the step (b) is longer than a gas supplytime of each of the gases in the step (a-2).

Preferably, a temperature of the substrate in the step (b) is higherthan a temperature of the substrate in the step (a).

Preferably, the step (a) and the step (b) are alternately repeated.

Preferably, in the step (a-2), the oxygen-containing gas is reacted withthe hydrogen-containing gas under the heated atmosphere having thepressure lower than the atmospheric pressure to form an oxidizingspecies, and the silicon-containing layer is changed into the siliconoxide layer by using the oxidizing species, and

in the step (b), the oxygen-containing gas is reacted with thehydrogen-containing gas under the heated atmosphere having the pressurelower than the atmospheric pressure to form the oxidizing species, andthe silicon oxide film is modified using the oxidizing species.

According to another embodiment of the present invention, there isprovided a substrate processing apparatus including:

a process vessel configured to accommodate a substrate;

a heater configured to heat an inside of the process vessel;

a source gas supply system configured to supply a source gas containinga predetermined element into the process vessel;

an oxygen-containing gas supply system configured to supply anoxygen-containing gas into the process vessel;

a hydrogen-containing gas supply system configured to supply ahydrogen-containing gas into the process vessel;

an exhaust system configured to exhaust the inside of the processvessel;

a pressure regulator configured to control pressure of the inside of theprocess vessel; and

a controller configured to control the heater, the source gas supplysystem, the oxygen-containing gas supply system, the hydrogen-containinggas supply system, the exhaust system, and the pressure regulator so asto perform:

(a) forming an oxide film having a predetermined thickness on thesubstrate by alternately repeating: (a-1) forming a layer containing thepredetermined element on the substrate by supplying the source gas intoa process vessel accommodating the substrate and exhausting the sourcegas from the process vessel; and (a-2) changing the layer containing thepredetermined element into an oxide layer by supplying anoxygen-containing gas and an hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under a heatedatmosphere having a pressure lower than an atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel; and

(b) modifying the oxide film formed on the substrate by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel, wherein the inside of the process vessel is under the heatedatmosphere having the pressure lower than the atmospheric pressure, andexhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel.

According to another embodiment of the present invention, there isprovided a substrate processing apparatus including:

a process vessel configured to accommodate a substrate;

a heater configured to heat an inside of the process vessel;

a source gas supply system configured to supply a source gas containinga silicon into the process vessel;

an oxygen-containing gas supply system configured to supply anoxygen-containing gas into the process vessel;

a hydrogen-containing gas supply system configured to supply ahydrogen-containing gas into the process vessel;

an exhaust system configured to exhaust the inside of the processvessel;

a pressure regulator configured to control pressure of the inside of theprocess vessel; and

a controller configured to control the heater, the source gas supplysystem, the oxygen-containing gas supply system, the hydrogen-containinggas supply system, the exhaust system, and the pressure regulator so asto perform:

(a) forming an silicon oxide film having a predetermined thickness onthe substrate by alternately repeating: (a-1) forming thesilicon-containing layer on the substrate by supplying the source gasinto a process vessel accommodating the substrate and exhausting thesource gas from the process vessel; and (a-2) changing the layercontaining the predetermined element into an silicon oxide layer bysupplying an oxygen-containing gas and an hydrogen-containing gas intothe process vessel, wherein the inside of the process vessel is under aheated atmosphere having a pressure lower than an atmospheric pressure,and exhausting the oxygen-containing gas and the hydrogen-containing gasfrom the process vessel; and

(b) modifying the silicon oxide film formed on the substrate bysupplying the oxygen-containing gas and the hydrogen-containing gas intothe process vessel, wherein the inside of the process vessel is underthe heated atmosphere having the pressure lower than the atmosphericpressure, and exhausting the oxygen-containing gas and thehydrogen-containing gas from the process vessel.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: (a) forming a metal oxide film on a substrate by alternatelyperforming: (a-1) forming a layer containing a metal element bysupplying a source gas containing the metal element to the substrate ina process vessel; and (a-2) changing the layer containing the metalelement into a metal oxide layer by supplying an oxygen-containing gasand a hydrogen-containing gas, which are activated by heat or plasma, tothe substrate in the process vessel, wherein an inside of the processvessel is under a heated atmosphere having a pressure lower than anatmospheric pressure; and (b) modifying the metal oxide film formed onthe substrate by supplying the oxygen-containing gas and thehydrogen-containing gas, which are activated by heat or plasma, to thesubstrate in the process vessel, wherein the inside of the processvessel is under a heated atmosphere having a pressure lower than theatmospheric pressure.
 2. The method of claim 1, wherein a temperature ofthe substrate in the (b) is higher than a temperature of the substratein the (a-2); or a gas supply time of each of the gases in the (b) islonger than a gas supply time of each of the gases in the (a-2).
 3. Themethod of claim 1, wherein a temperature of the substrate in the (b) ishigher than a temperature of the substrate in the (a).
 4. The method ofclaim 1, wherein a temperature of the substrate in the (b) is same as atemperature of the substrate in the (a).
 5. The method of claim 1,wherein the (a) and the (b) are alternately repeated.
 6. The method ofclaim 1, wherein in the (a-2), the oxygen-containing gas is reacted withthe hydrogen-containing gas to form an oxidizing species, and the layercontaining the metal element is changed into the metal oxide layer byusing the oxidizing species, and in the (b), the oxygen-containing gasis reacted with the hydrogen-containing gas to form the oxidizingspecies, and the metal oxide film is modified using the oxidizingspecies.
 7. The method of claim 1, wherein in the (a-2), theoxygen-containing gas is reacted with the hydrogen-containing gas toform atomic oxygen, and the layer containing the metal element ischanged into the metal oxide layer by using the atomic oxygen, and inthe (b), the oxygen-containing gas is reacted with thehydrogen-containing gas to form the atomic oxygen, and the metal oxidefilm is modified using the atomic oxygen.
 8. The method of claim 1,wherein the oxygen-containing gas comprises at least one selected from agroup consisting of O₂ gas and O₃ gas and the hydrogen-containing gascomprises at least one selected from a group consisting of H₂ gas and D₂gas.
 9. The method of claim 1, wherein the metal element comprises atleast one selected from a group consisting of zirconium (Zr), hafnium(Hf), titanium (Ti), and aluminium (Al).
 10. The method of claim 1,wherein the metal oxide film comprises a high permittivity insulatingfilm.
 11. A method of manufacturing a semiconductor device, comprising:(a) forming a metal oxide film on a substrate by alternately performing:(a-1) forming a layer containing a metal element by supplying a sourcegas containing the metal element to the substrate in a process vessel;and (a-2) changing the layer containing the metal element into a metaloxide layer by supplying a first oxygen-containing gas, which isactivated by heat or plasma, to the substrate in the process vessel,wherein an inside of the process vessel is under a heated atmospherehaving a pressure lower than an atmospheric pressure; and (b) modifyingthe metal oxide film formed on the substrate by supplying a secondoxygen-containing gas and a hydrogen-containing gas, which are activatedby heat or plasma, to the substrate in the process vessel, wherein theinside of the process vessel is under a heated atmosphere having apressure lower than the atmospheric pressure.
 12. The method of claim11, wherein the (a) and the (b) are alternately repeated.
 13. The methodof claim 11, wherein the first oxygen-containing gas comprises at leastone selected from a group consisting of O₂ gas, O₃ gas and H₂O gas, thesecond oxygen-containing gas comprises at least one selected from agroup consisting of O₂ gas and O₃ gas, and the hydrogen-containing gascomprises at least one selected from a group consisting of H₂ gas and D₂gas.
 14. A method of manufacturing a semiconductor device, comprising:(a) forming a metal oxide film on a substrate by alternately performing:(a-1) forming a layer containing a metal element by supplying a sourcegas containing the metal element to the substrate in a process vessel;and (a-2) changing the layer containing the metal element into a metaloxide layer by supplying a first oxygen-containing gas, which isactivated by heat or plasma, to the substrate in the process vessel,wherein an inside of the process vessel is under a heated atmospherehaving a pressure lower than an atmospheric pressure; and (b) modifyingthe metal oxide film formed on the substrate by supplying a secondoxygen-containing gas and a hydrogen-containing gas, which are activatedby heat or at least one of which is activated by plasma, to thesubstrate in the process vessel, wherein the inside of the processvessel is under a heated atmosphere having a pressure lower than theatmospheric pressure.